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 Page 1


Free coa M 
 
S      S    S    S               
 ote   
(a)  evolution a out the x axis    he  urve  surfa e S of soli  generate   y the revolution  a out x axis  
of the  area  oun e   y the  urve y f (x) the or inates x a x   an  the x axis is 
?  y s  
 
   
        ?  y
 
 
 s
 x
  x         S ?  y
 
 
v
,  (
 y
 x
)
 
- x  
where s is the length of the ar  measure  from x a to any p P(x y)  
( )  evolution a out the y axis  Similarly the  urve  surfa e S of the soli  gegerate   y the revolutions a out the 
x axis of the area  oun e   y the  urve x f(y) the lines y a y   an  the y axis is 
 ?  x s
 
   
 
where s is the length of the ar  measure  from y a to any point (x y)   
S ?  x
 s
 y
 y
 
 
            S ?  xv
(  (
 x
 y
)
 
) y
 
 
 
( ) Surfa e formula for Parametri  equations   et the given  urve  e x f(t) y f(t)  he  urve  surfa e of the soli   
forme   y the revolution a out the x axis is  
 ?  y
 s
 t
 t                ( etween the suita le limits) 
 or the ar  of the  ur le lying in the  st qua rant x varies from   to a   
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
- 
Similarly the  urve  surfa es S of the soli  forme   y the revolution a out the y axis is ?  x
 s
 t
 t 
( etween proper limits) 
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-  
( ) Surfa e formula for Polar equations   et the equation of the  urve  e r f( )  hen the  urve  surfa e generate   
 y the revolution a out the initial line of the ar  inter epte   etween the ra ii ve tors     an      is 
?  (rsin )
 s
  
  
 
   
 
where
 s
  
 v
,r
 
 (
 r
  
)
 
- 
s ?  y
 s
 r
 r 
where
 s
 r
 v
,  (r
  
 r
)
 
-  
 ote  he surfa e of a sphere of ra ius a is   a
 
 
 x     in  surfa e of a  one whose semi verti al angle is   an   ase a  ir le of ra ius r   
Solution  he generating  urve is  
y xtan               
 y
 x
 tan  
         
 s
 x
 v
,  (
 y
 x
)
 
- v*  tan
 
 + se   
 en e the require  surfa e is  
  ? y s   
     
 
? y
 s
 x
  x
     
 
   ? (xtan )
     
 
(se  ) x   se  tan *
x
 
 
+
 
     
  r
 
 s   
 x     in  the area of the surfa e forme   y the revolution of para ola y
 
  ax a out the x axis  y the ar  from the 
vertex to one en  of the latus re tum  
Solution  he given equation is y
 
  ax                                                                                                                                           (i)  
 ifferentiating (i) w r t x we get  
 y
 y
 x
  a       
 y
 x
 
 a
y
 
Page 2


Free coa M 
 
S      S    S    S               
 ote   
(a)  evolution a out the x axis    he  urve  surfa e S of soli  generate   y the revolution  a out x axis  
of the  area  oun e   y the  urve y f (x) the or inates x a x   an  the x axis is 
?  y s  
 
   
        ?  y
 
 
 s
 x
  x         S ?  y
 
 
v
,  (
 y
 x
)
 
- x  
where s is the length of the ar  measure  from x a to any p P(x y)  
( )  evolution a out the y axis  Similarly the  urve  surfa e S of the soli  gegerate   y the revolutions a out the 
x axis of the area  oun e   y the  urve x f(y) the lines y a y   an  the y axis is 
 ?  x s
 
   
 
where s is the length of the ar  measure  from y a to any point (x y)   
S ?  x
 s
 y
 y
 
 
            S ?  xv
(  (
 x
 y
)
 
) y
 
 
 
( ) Surfa e formula for Parametri  equations   et the given  urve  e x f(t) y f(t)  he  urve  surfa e of the soli   
forme   y the revolution a out the x axis is  
 ?  y
 s
 t
 t                ( etween the suita le limits) 
 or the ar  of the  ur le lying in the  st qua rant x varies from   to a   
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
- 
Similarly the  urve  surfa es S of the soli  forme   y the revolution a out the y axis is ?  x
 s
 t
 t 
( etween proper limits) 
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-  
( ) Surfa e formula for Polar equations   et the equation of the  urve  e r f( )  hen the  urve  surfa e generate   
 y the revolution a out the initial line of the ar  inter epte   etween the ra ii ve tors     an      is 
?  (rsin )
 s
  
  
 
   
 
where
 s
  
 v
,r
 
 (
 r
  
)
 
- 
s ?  y
 s
 r
 r 
where
 s
 r
 v
,  (r
  
 r
)
 
-  
 ote  he surfa e of a sphere of ra ius a is   a
 
 
 x     in  surfa e of a  one whose semi verti al angle is   an   ase a  ir le of ra ius r   
Solution  he generating  urve is  
y xtan               
 y
 x
 tan  
         
 s
 x
 v
,  (
 y
 x
)
 
- v*  tan
 
 + se   
 en e the require  surfa e is  
  ? y s   
     
 
? y
 s
 x
  x
     
 
   ? (xtan )
     
 
(se  ) x   se  tan *
x
 
 
+
 
     
  r
 
 s   
 x     in  the area of the surfa e forme   y the revolution of para ola y
 
  ax a out the x axis  y the ar  from the 
vertex to one en  of the latus re tum  
Solution  he given equation is y
 
  ax                                                                                                                                           (i)  
 ifferentiating (i) w r t x we get  
 y
 y
 x
  a       
 y
 x
 
 a
y
 
Free coach AM 
 
                    
 s
 x
 v
,  (
 y
 x
)
 
- v,  
 a
 
y
 
-  va 
v(x a)
y
 
 o r the require  surfa e x varies from   to a   
 en e the require  surfa e 
 ?  y
 s
 x
 x
 
 
 
   ? y 
 vav(x a)
y
 x
 
 
 
   va? (x a)
  /
 
 
 x   va{
 
 
(x a)
  /
}
 
 
 
  va
 
[( a )
  /
 a
  /
] 
 
 
 a
 
[ v   ] 
 x     in  the surfa e of the soli  forme   y the revolution a out x axis of the loop of the  urve x t
 
 y t 
 
 
t
 
 
Solution  he given equations are  
x t
 
 y t 
 
 
t
 
                         
 x
 t
  t         an        
 y
 t
 (  t
 
) 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-              
 s
 t
 v* t
 
 (  t
 
)
 
+ v(  t
 
)
 
 
        
 s
 t
 (  t
 
) 
Putting y   we get t   an  t v   
 en e for the loop t varies from   to v  
 he require  surfa e  
 ?  y s 
   ? y
 s
 t
 t
v 
 
 
   ? (t 
 
 
t
 
)
v 
 
(  t
 
) t 
 
  
 
? ( t  t
 
 t
 
) t
v 
 
 
  
 
[
 
 
t
 
 
 
 
t
 
 
 
 
t
 
]
 
v 
 
 
 
 [
 
 
 
 
 
 
 
 
]     
 x     in  the surfa e of the soli  generate   y the revolution of the astroi  x
  /
 y
  /
 or x a os
 
t y asin
 
t 
a out the x axis 
Solution  he given parametri  equations are  
x a os
 
t  y asin
 
t          
 x
 t
   a os
 
tsint an  
 y
 t
  a sin
 
t os t 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-            
 s
 t
 v( a
 
 os
 
sin
 
t  a
 
sin
 
t os
 
t) 
      
  
  
  a sint os t 
  en e the require  surfa e 
  ?  y
  /
 
 s
 t
 
   ? asin
 
t  a
  /
 
sint os t t 
    a
 
? sin
 
t
  /
 
 os t t 
   a
 
 
 ( erify ) 
 x     in  the surfa e area of the soli  generate   y revolving the  y loi  x a(  sin ) y a(   os ) 
a out the x axis   
Solution  he given parametri  equations are  
x a(  sin ) y a(   os )            
 x
  
 a(   os )            an      
 y
  
 asin  
            
 s
  
 v
,(
 x
  
)
 
 (
 y
  
)
 
- v*a
 
(   os )
 
 a
 
sin
 
 + av (   os ) 
 
Page 3


Free coa M 
 
S      S    S    S               
 ote   
(a)  evolution a out the x axis    he  urve  surfa e S of soli  generate   y the revolution  a out x axis  
of the  area  oun e   y the  urve y f (x) the or inates x a x   an  the x axis is 
?  y s  
 
   
        ?  y
 
 
 s
 x
  x         S ?  y
 
 
v
,  (
 y
 x
)
 
- x  
where s is the length of the ar  measure  from x a to any p P(x y)  
( )  evolution a out the y axis  Similarly the  urve  surfa e S of the soli  gegerate   y the revolutions a out the 
x axis of the area  oun e   y the  urve x f(y) the lines y a y   an  the y axis is 
 ?  x s
 
   
 
where s is the length of the ar  measure  from y a to any point (x y)   
S ?  x
 s
 y
 y
 
 
            S ?  xv
(  (
 x
 y
)
 
) y
 
 
 
( ) Surfa e formula for Parametri  equations   et the given  urve  e x f(t) y f(t)  he  urve  surfa e of the soli   
forme   y the revolution a out the x axis is  
 ?  y
 s
 t
 t                ( etween the suita le limits) 
 or the ar  of the  ur le lying in the  st qua rant x varies from   to a   
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
- 
Similarly the  urve  surfa es S of the soli  forme   y the revolution a out the y axis is ?  x
 s
 t
 t 
( etween proper limits) 
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-  
( ) Surfa e formula for Polar equations   et the equation of the  urve  e r f( )  hen the  urve  surfa e generate   
 y the revolution a out the initial line of the ar  inter epte   etween the ra ii ve tors     an      is 
?  (rsin )
 s
  
  
 
   
 
where
 s
  
 v
,r
 
 (
 r
  
)
 
- 
s ?  y
 s
 r
 r 
where
 s
 r
 v
,  (r
  
 r
)
 
-  
 ote  he surfa e of a sphere of ra ius a is   a
 
 
 x     in  surfa e of a  one whose semi verti al angle is   an   ase a  ir le of ra ius r   
Solution  he generating  urve is  
y xtan               
 y
 x
 tan  
         
 s
 x
 v
,  (
 y
 x
)
 
- v*  tan
 
 + se   
 en e the require  surfa e is  
  ? y s   
     
 
? y
 s
 x
  x
     
 
   ? (xtan )
     
 
(se  ) x   se  tan *
x
 
 
+
 
     
  r
 
 s   
 x     in  the area of the surfa e forme   y the revolution of para ola y
 
  ax a out the x axis  y the ar  from the 
vertex to one en  of the latus re tum  
Solution  he given equation is y
 
  ax                                                                                                                                           (i)  
 ifferentiating (i) w r t x we get  
 y
 y
 x
  a       
 y
 x
 
 a
y
 
Free coach AM 
 
                    
 s
 x
 v
,  (
 y
 x
)
 
- v,  
 a
 
y
 
-  va 
v(x a)
y
 
 o r the require  surfa e x varies from   to a   
 en e the require  surfa e 
 ?  y
 s
 x
 x
 
 
 
   ? y 
 vav(x a)
y
 x
 
 
 
   va? (x a)
  /
 
 
 x   va{
 
 
(x a)
  /
}
 
 
 
  va
 
[( a )
  /
 a
  /
] 
 
 
 a
 
[ v   ] 
 x     in  the surfa e of the soli  forme   y the revolution a out x axis of the loop of the  urve x t
 
 y t 
 
 
t
 
 
Solution  he given equations are  
x t
 
 y t 
 
 
t
 
                         
 x
 t
  t         an        
 y
 t
 (  t
 
) 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-              
 s
 t
 v* t
 
 (  t
 
)
 
+ v(  t
 
)
 
 
        
 s
 t
 (  t
 
) 
Putting y   we get t   an  t v   
 en e for the loop t varies from   to v  
 he require  surfa e  
 ?  y s 
   ? y
 s
 t
 t
v 
 
 
   ? (t 
 
 
t
 
)
v 
 
(  t
 
) t 
 
  
 
? ( t  t
 
 t
 
) t
v 
 
 
  
 
[
 
 
t
 
 
 
 
t
 
 
 
 
t
 
]
 
v 
 
 
 
 [
 
 
 
 
 
 
 
 
]     
 x     in  the surfa e of the soli  generate   y the revolution of the astroi  x
  /
 y
  /
 or x a os
 
t y asin
 
t 
a out the x axis 
Solution  he given parametri  equations are  
x a os
 
t  y asin
 
t          
 x
 t
   a os
 
tsint an  
 y
 t
  a sin
 
t os t 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-            
 s
 t
 v( a
 
 os
 
sin
 
t  a
 
sin
 
t os
 
t) 
      
  
  
  a sint os t 
  en e the require  surfa e 
  ?  y
  /
 
 s
 t
 
   ? asin
 
t  a
  /
 
sint os t t 
    a
 
? sin
 
t
  /
 
 os t t 
   a
 
 
 ( erify ) 
 x     in  the surfa e area of the soli  generate   y revolving the  y loi  x a(  sin ) y a(   os ) 
a out the x axis   
Solution  he given parametri  equations are  
x a(  sin ) y a(   os )            
 x
  
 a(   os )            an      
 y
  
 asin  
            
 s
  
 v
,(
 x
  
)
 
 (
 y
  
)
 
- v*a
 
(   os )
 
 a
 
sin
 
 + av (   os ) 
 
Fre M 
 
    
 s
  
 a
v
 ( sin
 
 
 
)  a sin(
 
 
) 
 he require  surfa e area 
 ?  y
  
 
 s
  
    
   ? a(   os )
  
 
 a sin(
 
 
)   
   a
 
? sin
 
(  / )  
  
 
    a
 
? sin
 
(  / )  
 
 
 
  
 
 a
 
        ( erify ) 
 x     in  the area of the surfa e of revolving the  urve r  a os  a out the initial line 
Solution  he given  ure is r  a os                ( ) 
 ifferentiating ( ) w r t   we get 
 r
  
   a sin  
    
 s
  
 v
,r
 
 (
 r
  
)
 
- v* a
 
 os
 
   a
 
sin
 
 + 
    
 s
  
  a 
 en e the require  surfa e  
 ?  y
  /
 
 s
  
   
   ? rsin   a  
  /
 
  a ? a sin  os   
  /
 
   a
 
? sin  os   
  /
 
   a
 
          ( erify ) 
    in  the surfa e of the soli  generate   y the revolution of the lemnis ate r
 
 a
 
 os   a out the initial line 
Solution  he  urve is r
 
 a os   
 ifferentiating (i) w r t   we get 
 r
 r
  
   a
 
sin   
 r
  
  
a
 
sin  
r
 
 
 s
  
 
v
{ r
 
 (
 r
  
)} 
 v,a
 
 os   
a
 
sin
 
  
r
 
- 
 
r
 v*r
 
a
 
 os   a
 
sin
 
  + 
 
r
 v*a
 
 os
 
   a
 
sin
 
  + 
 
 s
  
 
a
 
r
 
 he require  surfa e 
  ?  y
 s
  
  
 
 
 
   ? rsin  
a
 
r
  
 
 
 
   a
 
? sin   
 
 
 
  v  a
 
(v   )                     verify 
    in  the surfa e of the soli  forme   y the revolution of  ar ioi  r a(   os ) a out the initial line  
Solution  he given  urve is r a(   os ) 
 r
  
  asin  
 
 s
  
 v
,r
 
 (
 r
  
)
 
- v*a
 
(   os )
 
 a
 
sin
 
 + 
 s
  
 av* (   os )+  a os
 
 
 
 en e the require  surfa e 
 ?  y
 s
  
  
 
 
 ?  rsin  a os
 
 
  
 
 
   ? a(   os )sin  a os
 
 
  
 
 
 
  
 
 a
 
             verify 
    in  the surfa e of the soli  forme   y the revolution of the  ar io  r a(   os ) a out the initial line 
Solution the given  urve is r a(   os ) 
 r
  
 asin  
 s
  
 
v
{ r
 
 (
 r
  
)} v*a
 
(   os )
 
 a
 
sin
 
 + 
 
Page 4


Free coa M 
 
S      S    S    S               
 ote   
(a)  evolution a out the x axis    he  urve  surfa e S of soli  generate   y the revolution  a out x axis  
of the  area  oun e   y the  urve y f (x) the or inates x a x   an  the x axis is 
?  y s  
 
   
        ?  y
 
 
 s
 x
  x         S ?  y
 
 
v
,  (
 y
 x
)
 
- x  
where s is the length of the ar  measure  from x a to any p P(x y)  
( )  evolution a out the y axis  Similarly the  urve  surfa e S of the soli  gegerate   y the revolutions a out the 
x axis of the area  oun e   y the  urve x f(y) the lines y a y   an  the y axis is 
 ?  x s
 
   
 
where s is the length of the ar  measure  from y a to any point (x y)   
S ?  x
 s
 y
 y
 
 
            S ?  xv
(  (
 x
 y
)
 
) y
 
 
 
( ) Surfa e formula for Parametri  equations   et the given  urve  e x f(t) y f(t)  he  urve  surfa e of the soli   
forme   y the revolution a out the x axis is  
 ?  y
 s
 t
 t                ( etween the suita le limits) 
 or the ar  of the  ur le lying in the  st qua rant x varies from   to a   
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
- 
Similarly the  urve  surfa es S of the soli  forme   y the revolution a out the y axis is ?  x
 s
 t
 t 
( etween proper limits) 
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-  
( ) Surfa e formula for Polar equations   et the equation of the  urve  e r f( )  hen the  urve  surfa e generate   
 y the revolution a out the initial line of the ar  inter epte   etween the ra ii ve tors     an      is 
?  (rsin )
 s
  
  
 
   
 
where
 s
  
 v
,r
 
 (
 r
  
)
 
- 
s ?  y
 s
 r
 r 
where
 s
 r
 v
,  (r
  
 r
)
 
-  
 ote  he surfa e of a sphere of ra ius a is   a
 
 
 x     in  surfa e of a  one whose semi verti al angle is   an   ase a  ir le of ra ius r   
Solution  he generating  urve is  
y xtan               
 y
 x
 tan  
         
 s
 x
 v
,  (
 y
 x
)
 
- v*  tan
 
 + se   
 en e the require  surfa e is  
  ? y s   
     
 
? y
 s
 x
  x
     
 
   ? (xtan )
     
 
(se  ) x   se  tan *
x
 
 
+
 
     
  r
 
 s   
 x     in  the area of the surfa e forme   y the revolution of para ola y
 
  ax a out the x axis  y the ar  from the 
vertex to one en  of the latus re tum  
Solution  he given equation is y
 
  ax                                                                                                                                           (i)  
 ifferentiating (i) w r t x we get  
 y
 y
 x
  a       
 y
 x
 
 a
y
 
Free coach AM 
 
                    
 s
 x
 v
,  (
 y
 x
)
 
- v,  
 a
 
y
 
-  va 
v(x a)
y
 
 o r the require  surfa e x varies from   to a   
 en e the require  surfa e 
 ?  y
 s
 x
 x
 
 
 
   ? y 
 vav(x a)
y
 x
 
 
 
   va? (x a)
  /
 
 
 x   va{
 
 
(x a)
  /
}
 
 
 
  va
 
[( a )
  /
 a
  /
] 
 
 
 a
 
[ v   ] 
 x     in  the surfa e of the soli  forme   y the revolution a out x axis of the loop of the  urve x t
 
 y t 
 
 
t
 
 
Solution  he given equations are  
x t
 
 y t 
 
 
t
 
                         
 x
 t
  t         an        
 y
 t
 (  t
 
) 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-              
 s
 t
 v* t
 
 (  t
 
)
 
+ v(  t
 
)
 
 
        
 s
 t
 (  t
 
) 
Putting y   we get t   an  t v   
 en e for the loop t varies from   to v  
 he require  surfa e  
 ?  y s 
   ? y
 s
 t
 t
v 
 
 
   ? (t 
 
 
t
 
)
v 
 
(  t
 
) t 
 
  
 
? ( t  t
 
 t
 
) t
v 
 
 
  
 
[
 
 
t
 
 
 
 
t
 
 
 
 
t
 
]
 
v 
 
 
 
 [
 
 
 
 
 
 
 
 
]     
 x     in  the surfa e of the soli  generate   y the revolution of the astroi  x
  /
 y
  /
 or x a os
 
t y asin
 
t 
a out the x axis 
Solution  he given parametri  equations are  
x a os
 
t  y asin
 
t          
 x
 t
   a os
 
tsint an  
 y
 t
  a sin
 
t os t 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-            
 s
 t
 v( a
 
 os
 
sin
 
t  a
 
sin
 
t os
 
t) 
      
  
  
  a sint os t 
  en e the require  surfa e 
  ?  y
  /
 
 s
 t
 
   ? asin
 
t  a
  /
 
sint os t t 
    a
 
? sin
 
t
  /
 
 os t t 
   a
 
 
 ( erify ) 
 x     in  the surfa e area of the soli  generate   y revolving the  y loi  x a(  sin ) y a(   os ) 
a out the x axis   
Solution  he given parametri  equations are  
x a(  sin ) y a(   os )            
 x
  
 a(   os )            an      
 y
  
 asin  
            
 s
  
 v
,(
 x
  
)
 
 (
 y
  
)
 
- v*a
 
(   os )
 
 a
 
sin
 
 + av (   os ) 
 
Fre M 
 
    
 s
  
 a
v
 ( sin
 
 
 
)  a sin(
 
 
) 
 he require  surfa e area 
 ?  y
  
 
 s
  
    
   ? a(   os )
  
 
 a sin(
 
 
)   
   a
 
? sin
 
(  / )  
  
 
    a
 
? sin
 
(  / )  
 
 
 
  
 
 a
 
        ( erify ) 
 x     in  the area of the surfa e of revolving the  urve r  a os  a out the initial line 
Solution  he given  ure is r  a os                ( ) 
 ifferentiating ( ) w r t   we get 
 r
  
   a sin  
    
 s
  
 v
,r
 
 (
 r
  
)
 
- v* a
 
 os
 
   a
 
sin
 
 + 
    
 s
  
  a 
 en e the require  surfa e  
 ?  y
  /
 
 s
  
   
   ? rsin   a  
  /
 
  a ? a sin  os   
  /
 
   a
 
? sin  os   
  /
 
   a
 
          ( erify ) 
    in  the surfa e of the soli  generate   y the revolution of the lemnis ate r
 
 a
 
 os   a out the initial line 
Solution  he  urve is r
 
 a os   
 ifferentiating (i) w r t   we get 
 r
 r
  
   a
 
sin   
 r
  
  
a
 
sin  
r
 
 
 s
  
 
v
{ r
 
 (
 r
  
)} 
 v,a
 
 os   
a
 
sin
 
  
r
 
- 
 
r
 v*r
 
a
 
 os   a
 
sin
 
  + 
 
r
 v*a
 
 os
 
   a
 
sin
 
  + 
 
 s
  
 
a
 
r
 
 he require  surfa e 
  ?  y
 s
  
  
 
 
 
   ? rsin  
a
 
r
  
 
 
 
   a
 
? sin   
 
 
 
  v  a
 
(v   )                     verify 
    in  the surfa e of the soli  forme   y the revolution of  ar ioi  r a(   os ) a out the initial line  
Solution  he given  urve is r a(   os ) 
 r
  
  asin  
 
 s
  
 v
,r
 
 (
 r
  
)
 
- v*a
 
(   os )
 
 a
 
sin
 
 + 
 s
  
 av* (   os )+  a os
 
 
 
 en e the require  surfa e 
 ?  y
 s
  
  
 
 
 ?  rsin  a os
 
 
  
 
 
   ? a(   os )sin  a os
 
 
  
 
 
 
  
 
 a
 
             verify 
    in  the surfa e of the soli  forme   y the revolution of the  ar io  r a(   os ) a out the initial line 
Solution the given  urve is r a(   os ) 
 r
  
 asin  
 s
  
 
v
{ r
 
 (
 r
  
)} v*a
 
(   os )
 
 a
 
sin
 
 + 
 
Free co 
 
 
 s
  
 av (   os )  a sin
 
 
 
require  surfa e 
 ?  y
 s
  
  
 
 
   ? rsin  a sin
 
 
  
 
 
   a
 
?(   os )sin sin
 
 
  
 
 
    a
 
? os
 
 
sin
 
 
 
  
 
 
   a
 
     verify 
                 
 
 
 x      ? ? (x
 
 y
 
) x y
 
 
 
 
 
Sol
 
   ? (x
 
y 
y
 
 
)
 
 
 x
 
 
 ? (x
 
    ) (
 
 
  ) x ?
( x
 
 
 
 
) x (
 x
 
 
 
 x
 
)
 
 
 
  
 
 
 
 
 
 
  
 x    ? ? (x
 
 y
 
) x y
 
 
 
 
 
Sol
 
  ? (x
 
y 
y
 
 
)
 
 
 x
 
 
 ? (x
 
 
x
 
 
) x
 
 
 *
x
 
 
 
x
 
  
+
 
 
 
 
 
 
 
  
 
 
 
  
 x   ? ? xy  x y
 
 
 
 
 
Sol
 
  ? x x ? y y
 
 
 
 
          (
x
 
 
)
 
 
(
y
 
 
)
 
 
 
 
 
     
 x     valuate ? ?    xy
 
 y x
v 
 
 
 
 
 
Sol
 
  ? ?    xy
 
 y x
v 
 
 
 
 
 ? 0  x y
 
|
   
 
  v 
1  x     
 
 
                              , x is treate  as a  onstant- 
                                                    ? 0  x (vx)
 
   x (x
 
)
 
1 x
 
 
 ? ,  x
 
   x
 
- x
 
 
 ,  x
 
  x
  
-
 
 
   
 x    ?xy(x
 
 y
 
) x y
 
   ,  a    - 
Sol
 
    ??xy(x
 
 y
 
) x y
 
  ? ? xy(x
 
 y
 
) x y
 
   
 
   
  
 ? ? (x
 
y xy
 
)
 
   
  x y
 
   
 
 ? x *
x
 
y
 
 
 
xy
 
 
+
 
 
 
a
 
 
 
 
(a
 
  
 
  )               ( erify ) 
 
   
 
    or the fun tion f  efine  y f(x y) 
{
 
      
 
y
 
            if   x y  
 
 
x
 
             if   y x  
 Show that? x
 
 
? f y
 
 
 ? y ? f x
 
 
 
 
  
Solution  onsi er ? f y
 
 
 ? f y 
 
 
? f y
 
 
 
 ? 
 
x
 
 y ?
 
y
 
 y
 
 
 
 
 0 
y
x
 
1
 
 
 [ 
 
y
]
 
 
  
 
x
 (  ) 
 
x
    
? (  ) x
 
 
  (x)
 
 
    
            ? x
 
 
? f y
 
 
      
? f x
 
 
 ? f x ? f x
 
 
 
 
 
 ?
 
y
 
 x
 
 
 ? 
 
x
 
 x
 
 
 [
x
y
 
]
 
 
 [
 
x
]
 
 
 
 
y
   
 
y
   
              ?   y
 
 
 (y)
 
 
   
              ? y
 
 
? f x
 
 
   
Page 5


Free coa M 
 
S      S    S    S               
 ote   
(a)  evolution a out the x axis    he  urve  surfa e S of soli  generate   y the revolution  a out x axis  
of the  area  oun e   y the  urve y f (x) the or inates x a x   an  the x axis is 
?  y s  
 
   
        ?  y
 
 
 s
 x
  x         S ?  y
 
 
v
,  (
 y
 x
)
 
- x  
where s is the length of the ar  measure  from x a to any p P(x y)  
( )  evolution a out the y axis  Similarly the  urve  surfa e S of the soli  gegerate   y the revolutions a out the 
x axis of the area  oun e   y the  urve x f(y) the lines y a y   an  the y axis is 
 ?  x s
 
   
 
where s is the length of the ar  measure  from y a to any point (x y)   
S ?  x
 s
 y
 y
 
 
            S ?  xv
(  (
 x
 y
)
 
) y
 
 
 
( ) Surfa e formula for Parametri  equations   et the given  urve  e x f(t) y f(t)  he  urve  surfa e of the soli   
forme   y the revolution a out the x axis is  
 ?  y
 s
 t
 t                ( etween the suita le limits) 
 or the ar  of the  ur le lying in the  st qua rant x varies from   to a   
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
- 
Similarly the  urve  surfa es S of the soli  forme   y the revolution a out the y axis is ?  x
 s
 t
 t 
( etween proper limits) 
where
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-  
( ) Surfa e formula for Polar equations   et the equation of the  urve  e r f( )  hen the  urve  surfa e generate   
 y the revolution a out the initial line of the ar  inter epte   etween the ra ii ve tors     an      is 
?  (rsin )
 s
  
  
 
   
 
where
 s
  
 v
,r
 
 (
 r
  
)
 
- 
s ?  y
 s
 r
 r 
where
 s
 r
 v
,  (r
  
 r
)
 
-  
 ote  he surfa e of a sphere of ra ius a is   a
 
 
 x     in  surfa e of a  one whose semi verti al angle is   an   ase a  ir le of ra ius r   
Solution  he generating  urve is  
y xtan               
 y
 x
 tan  
         
 s
 x
 v
,  (
 y
 x
)
 
- v*  tan
 
 + se   
 en e the require  surfa e is  
  ? y s   
     
 
? y
 s
 x
  x
     
 
   ? (xtan )
     
 
(se  ) x   se  tan *
x
 
 
+
 
     
  r
 
 s   
 x     in  the area of the surfa e forme   y the revolution of para ola y
 
  ax a out the x axis  y the ar  from the 
vertex to one en  of the latus re tum  
Solution  he given equation is y
 
  ax                                                                                                                                           (i)  
 ifferentiating (i) w r t x we get  
 y
 y
 x
  a       
 y
 x
 
 a
y
 
Free coach AM 
 
                    
 s
 x
 v
,  (
 y
 x
)
 
- v,  
 a
 
y
 
-  va 
v(x a)
y
 
 o r the require  surfa e x varies from   to a   
 en e the require  surfa e 
 ?  y
 s
 x
 x
 
 
 
   ? y 
 vav(x a)
y
 x
 
 
 
   va? (x a)
  /
 
 
 x   va{
 
 
(x a)
  /
}
 
 
 
  va
 
[( a )
  /
 a
  /
] 
 
 
 a
 
[ v   ] 
 x     in  the surfa e of the soli  forme   y the revolution a out x axis of the loop of the  urve x t
 
 y t 
 
 
t
 
 
Solution  he given equations are  
x t
 
 y t 
 
 
t
 
                         
 x
 t
  t         an        
 y
 t
 (  t
 
) 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-              
 s
 t
 v* t
 
 (  t
 
)
 
+ v(  t
 
)
 
 
        
 s
 t
 (  t
 
) 
Putting y   we get t   an  t v   
 en e for the loop t varies from   to v  
 he require  surfa e  
 ?  y s 
   ? y
 s
 t
 t
v 
 
 
   ? (t 
 
 
t
 
)
v 
 
(  t
 
) t 
 
  
 
? ( t  t
 
 t
 
) t
v 
 
 
  
 
[
 
 
t
 
 
 
 
t
 
 
 
 
t
 
]
 
v 
 
 
 
 [
 
 
 
 
 
 
 
 
]     
 x     in  the surfa e of the soli  generate   y the revolution of the astroi  x
  /
 y
  /
 or x a os
 
t y asin
 
t 
a out the x axis 
Solution  he given parametri  equations are  
x a os
 
t  y asin
 
t          
 x
 t
   a os
 
tsint an  
 y
 t
  a sin
 
t os t 
            
 s
 t
 v
,(
 x
 t
)
 
 (
 y
 t
)
 
-            
 s
 t
 v( a
 
 os
 
sin
 
t  a
 
sin
 
t os
 
t) 
      
  
  
  a sint os t 
  en e the require  surfa e 
  ?  y
  /
 
 s
 t
 
   ? asin
 
t  a
  /
 
sint os t t 
    a
 
? sin
 
t
  /
 
 os t t 
   a
 
 
 ( erify ) 
 x     in  the surfa e area of the soli  generate   y revolving the  y loi  x a(  sin ) y a(   os ) 
a out the x axis   
Solution  he given parametri  equations are  
x a(  sin ) y a(   os )            
 x
  
 a(   os )            an      
 y
  
 asin  
            
 s
  
 v
,(
 x
  
)
 
 (
 y
  
)
 
- v*a
 
(   os )
 
 a
 
sin
 
 + av (   os ) 
 
Fre M 
 
    
 s
  
 a
v
 ( sin
 
 
 
)  a sin(
 
 
) 
 he require  surfa e area 
 ?  y
  
 
 s
  
    
   ? a(   os )
  
 
 a sin(
 
 
)   
   a
 
? sin
 
(  / )  
  
 
    a
 
? sin
 
(  / )  
 
 
 
  
 
 a
 
        ( erify ) 
 x     in  the area of the surfa e of revolving the  urve r  a os  a out the initial line 
Solution  he given  ure is r  a os                ( ) 
 ifferentiating ( ) w r t   we get 
 r
  
   a sin  
    
 s
  
 v
,r
 
 (
 r
  
)
 
- v* a
 
 os
 
   a
 
sin
 
 + 
    
 s
  
  a 
 en e the require  surfa e  
 ?  y
  /
 
 s
  
   
   ? rsin   a  
  /
 
  a ? a sin  os   
  /
 
   a
 
? sin  os   
  /
 
   a
 
          ( erify ) 
    in  the surfa e of the soli  generate   y the revolution of the lemnis ate r
 
 a
 
 os   a out the initial line 
Solution  he  urve is r
 
 a os   
 ifferentiating (i) w r t   we get 
 r
 r
  
   a
 
sin   
 r
  
  
a
 
sin  
r
 
 
 s
  
 
v
{ r
 
 (
 r
  
)} 
 v,a
 
 os   
a
 
sin
 
  
r
 
- 
 
r
 v*r
 
a
 
 os   a
 
sin
 
  + 
 
r
 v*a
 
 os
 
   a
 
sin
 
  + 
 
 s
  
 
a
 
r
 
 he require  surfa e 
  ?  y
 s
  
  
 
 
 
   ? rsin  
a
 
r
  
 
 
 
   a
 
? sin   
 
 
 
  v  a
 
(v   )                     verify 
    in  the surfa e of the soli  forme   y the revolution of  ar ioi  r a(   os ) a out the initial line  
Solution  he given  urve is r a(   os ) 
 r
  
  asin  
 
 s
  
 v
,r
 
 (
 r
  
)
 
- v*a
 
(   os )
 
 a
 
sin
 
 + 
 s
  
 av* (   os )+  a os
 
 
 
 en e the require  surfa e 
 ?  y
 s
  
  
 
 
 ?  rsin  a os
 
 
  
 
 
   ? a(   os )sin  a os
 
 
  
 
 
 
  
 
 a
 
             verify 
    in  the surfa e of the soli  forme   y the revolution of the  ar io  r a(   os ) a out the initial line 
Solution the given  urve is r a(   os ) 
 r
  
 asin  
 s
  
 
v
{ r
 
 (
 r
  
)} v*a
 
(   os )
 
 a
 
sin
 
 + 
 
Free co 
 
 
 s
  
 av (   os )  a sin
 
 
 
require  surfa e 
 ?  y
 s
  
  
 
 
   ? rsin  a sin
 
 
  
 
 
   a
 
?(   os )sin sin
 
 
  
 
 
    a
 
? os
 
 
sin
 
 
 
  
 
 
   a
 
     verify 
                 
 
 
 x      ? ? (x
 
 y
 
) x y
 
 
 
 
 
Sol
 
   ? (x
 
y 
y
 
 
)
 
 
 x
 
 
 ? (x
 
    ) (
 
 
  ) x ?
( x
 
 
 
 
) x (
 x
 
 
 
 x
 
)
 
 
 
  
 
 
 
 
 
 
  
 x    ? ? (x
 
 y
 
) x y
 
 
 
 
 
Sol
 
  ? (x
 
y 
y
 
 
)
 
 
 x
 
 
 ? (x
 
 
x
 
 
) x
 
 
 *
x
 
 
 
x
 
  
+
 
 
 
 
 
 
 
  
 
 
 
  
 x   ? ? xy  x y
 
 
 
 
 
Sol
 
  ? x x ? y y
 
 
 
 
          (
x
 
 
)
 
 
(
y
 
 
)
 
 
 
 
 
     
 x     valuate ? ?    xy
 
 y x
v 
 
 
 
 
 
Sol
 
  ? ?    xy
 
 y x
v 
 
 
 
 
 ? 0  x y
 
|
   
 
  v 
1  x     
 
 
                              , x is treate  as a  onstant- 
                                                    ? 0  x (vx)
 
   x (x
 
)
 
1 x
 
 
 ? ,  x
 
   x
 
- x
 
 
 ,  x
 
  x
  
-
 
 
   
 x    ?xy(x
 
 y
 
) x y
 
   ,  a    - 
Sol
 
    ??xy(x
 
 y
 
) x y
 
  ? ? xy(x
 
 y
 
) x y
 
   
 
   
  
 ? ? (x
 
y xy
 
)
 
   
  x y
 
   
 
 ? x *
x
 
y
 
 
 
xy
 
 
+
 
 
 
a
 
 
 
 
(a
 
  
 
  )               ( erify ) 
 
   
 
    or the fun tion f  efine  y f(x y) 
{
 
      
 
y
 
            if   x y  
 
 
x
 
             if   y x  
 Show that? x
 
 
? f y
 
 
 ? y ? f x
 
 
 
 
  
Solution  onsi er ? f y
 
 
 ? f y 
 
 
? f y
 
 
 
 ? 
 
x
 
 y ?
 
y
 
 y
 
 
 
 
 0 
y
x
 
1
 
 
 [ 
 
y
]
 
 
  
 
x
 (  ) 
 
x
    
? (  ) x
 
 
  (x)
 
 
    
            ? x
 
 
? f y
 
 
      
? f x
 
 
 ? f x ? f x
 
 
 
 
 
 ?
 
y
 
 x
 
 
 ? 
 
x
 
 x
 
 
 [
x
y
 
]
 
 
 [
 
x
]
 
 
 
 
y
   
 
y
   
              ?   y
 
 
 (y)
 
 
   
              ? y
 
 
? f x
 
 
   
Free coa 
 
              ? x
 
 
? f y
 
 
 ? y
 
 
? f x
 
 
 
 x     f f(x y)     {
 y
 
                           x y  
 x
 
                           y x  
                            otherwise     
 
Prove that ? x 
 
 
? f(x y) y
 
 
 ? y 
 
 
? f(x y) x
 
 
  
 
 
 
Solution  onsi er 
? f(x y) y
 
 
 ? f(x y) y
 
   
 ? f(x y) y
 
   
 
 ? ( x
 
) y
 
   
 ? ( y
 
) y
 
   
 ( x
 
)(y)
 
 
 (
y
 
 
)
 
 
  x
 
 (x  ) 
 
 
(  x
 
)  
 
 
x
 
 
 
 
 
                ? x
 
 
? f(x y) y
 
 
  ? (
 
 
x
 
 
 
 
) x
 
 
  
 
 
                                                                                                                ( ) 
 gain  onsi er 
? f(x y) x
 
 
 ? f(x y) x
 
   
 ? f(x y) y
 
 
 ? ( y
 
) x
 
   
 ? ( x
 
) x
 
 
 ( y
 
)(x)
 
 
 (
x
 
 
)
 
 
  
 
 
y
 
 
 
 
 
? y 
 
 
? f(x y) x
 
 
  
 
 
                                                                                                                                                           ( ) 
 from ( )   ( ) 
? x
 
 
? f(x y) y
 
 
 ? y
 
 
? f(x y) x
 
 
  
 
 
 
 hange of or er of  ntegration 
 x      ? { ? f(x y) y
v     
 
 
} x
 
 
 
x   x a     an      y x y 
v
 ax x
 
 
Solution  n solving y x an  y 
v
 ax x
 
 
  
v
 ax x
 
 x 
   ax x
 
 x
 
 
  x   x a 
 gain y 
v
 ax x
 
 
  y
 
  ax x
 
                      x
 
 y
 
  ax 
        (x a)
 
 y
 
 a
 
                  (x a)
 
 a
 
 y
 
 
           x a  va
 
 y
 
 
           x a va
 
 y
 
 
              ? { ? f(x y) y
v     
 
 
} x
 
 
 ? ,? f(x y) x
 
    v 
 
  
 
- y
 
   
 
    hange the or er of integration in the  ou le integral ? ? f(x y) x y
v   
v     
 
  
 
 
 int   ? ? f(x y) x y
v   
v     
 
  
 
  ? ? f(x y) y x
  
  
 
 
  
 ? ? f(x y) x y
  
    v 
 
  
 
 
 
   
 
   
? ? f(x y) x y
  
  
 
 
  
  
   
 
    hange the or er of integration ? x
 
 
? f(x y) y
v 
 
 
 int ? x
 
 
? f(x y) y
v 
 
 ? y
 
   
? f(x y) x
 
   
 
 
 x     y  hanging the or er of integration prove that   ? x
 
 
?
y y
(  xy)
 
(  y
 
)
 
   
 
  /
 
 
x   x           an     y x y 
 
x
 
   xy   ( e tangular  yper ola ) 
 n solving 
               xy                         an                     y x 
            x
 
                           x    
Read More
27 docs|150 tests

FAQs on Surfaces of Solids of Revolution - Topic-wise Tests & Solved Examples for Mathematics

1. What is a solid of revolution in mathematics?
A solid of revolution in mathematics is a three-dimensional shape that is formed by rotating a two-dimensional curve, called the generating curve, around a fixed axis of rotation. This rotation creates a solid shape with a circular cross-section at every point along the curve.
2. How are surfaces of solids of revolution calculated?
To calculate the surface area of a solid of revolution, we use the method of integration. Specifically, we integrate a certain formula, such as 2πy√(1+(dy/dx)^2) or 2πx√(1+(dx/dy)^2), where y or x represents the generating curve, and dy/dx or dx/dy represents the derivative of the generating curve with respect to x or y, respectively.
3. What are some common examples of solids of revolution?
Some common examples of solids of revolution include cylinders, cones, and spheres. For example, a cylinder is formed by rotating a rectangle around an axis, a cone is formed by rotating a right triangle around an axis, and a sphere is formed by rotating a semicircle around an axis.
4. How do solids of revolution relate to real-world applications?
Solids of revolution have numerous real-world applications. For instance, they can be used to model objects such as bottles, vases, and pipes. Additionally, they are employed in various fields, including engineering, architecture, and physics, to study and analyze the properties of objects that have rotational symmetry.
5. Are there any limitations or assumptions when calculating surfaces of solids of revolution?
Yes, there are some limitations and assumptions when calculating surfaces of solids of revolution. One major assumption is that the generating curve must be continuous and smooth. Discontinuities or sharp corners can lead to inaccurate calculations. Additionally, the method of integration assumes that the generating curve is revolved around a fixed axis without any deformation, which may not always hold true in real-world scenarios.
27 docs|150 tests
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