Page 1
16. Tangents and Normals
Exercise 16.1
1 A. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 4
Answer
Given:
y = at x = 4
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
y =
? y = (
? y =
(x
n
) = n.x
n – 1
The Slope of the tangent is
Since, x = 4
x = 4
=
x = 4
=
x = 4
=
x = 4
= 3
The Slope of the tangent at x = 4 is 3
Page 2
16. Tangents and Normals
Exercise 16.1
1 A. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 4
Answer
Given:
y = at x = 4
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
y =
? y = (
? y =
(x
n
) = n.x
n – 1
The Slope of the tangent is
Since, x = 4
x = 4
=
x = 4
=
x = 4
=
x = 4
= 3
The Slope of the tangent at x = 4 is 3
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 B. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 9
Answer
Given:
y = at x = 9
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
? y =
? y = (
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = (
Since, x = 9
x = 9
=
x = 9
=
x = 9
=
x = 9
=
x = 9
=
The Slope of the tangent at x = 9 is
? The Slope of the normal =
? The Slope of the normal =
Page 3
16. Tangents and Normals
Exercise 16.1
1 A. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 4
Answer
Given:
y = at x = 4
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
y =
? y = (
? y =
(x
n
) = n.x
n – 1
The Slope of the tangent is
Since, x = 4
x = 4
=
x = 4
=
x = 4
=
x = 4
= 3
The Slope of the tangent at x = 4 is 3
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 B. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 9
Answer
Given:
y = at x = 9
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
? y =
? y = (
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = (
Since, x = 9
x = 9
=
x = 9
=
x = 9
=
x = 9
=
x = 9
=
The Slope of the tangent at x = 9 is
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal = – 6
1 C. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
y = x
3
– x at x = 2
Answer
Given:
y = x
3
– x at x = 2
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = x
3
– x
(x
3
) + 3 (x)
= 3.x
3 – 1
– 1.x
1 – 0
= 3x
2
– 1
Since, x = 2
x = 2
= 3 (2)
2
– 1
x = 2
= (3 4) – 1
x = 2
= 12 – 1
x = 2
= 11
The Slope of the tangent at x = 2 is 11
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 D. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
y = 2x
2
+ 3 sin x at x = 0
Answer
Given:
y = 2x
2
+ 3sinx at x = 0
Page 4
16. Tangents and Normals
Exercise 16.1
1 A. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 4
Answer
Given:
y = at x = 4
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
y =
? y = (
? y =
(x
n
) = n.x
n – 1
The Slope of the tangent is
Since, x = 4
x = 4
=
x = 4
=
x = 4
=
x = 4
= 3
The Slope of the tangent at x = 4 is 3
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 B. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 9
Answer
Given:
y = at x = 9
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
? y =
? y = (
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = (
Since, x = 9
x = 9
=
x = 9
=
x = 9
=
x = 9
=
x = 9
=
The Slope of the tangent at x = 9 is
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal = – 6
1 C. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
y = x
3
– x at x = 2
Answer
Given:
y = x
3
– x at x = 2
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = x
3
– x
(x
3
) + 3 (x)
= 3.x
3 – 1
– 1.x
1 – 0
= 3x
2
– 1
Since, x = 2
x = 2
= 3 (2)
2
– 1
x = 2
= (3 4) – 1
x = 2
= 12 – 1
x = 2
= 11
The Slope of the tangent at x = 2 is 11
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 D. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
y = 2x
2
+ 3 sin x at x = 0
Answer
Given:
y = 2x
2
+ 3sinx at x = 0
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = 2x
2
+ 3sinx
=
2 (x
2
) + 3 (sinx)
= 2 2x
2 – 1
+ 3 (cosx)
(sinx) = cosx
= 4x + 3cosx
Since, x = 2
?
x = 0
= 4 0 + 3cos(0)
cos(0) = 1
?
x = 0
= 0 + 3 1
?
x = 0
= 3
The Slope of the tangent at x = 0 is 3
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 E. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
x = a (? – sin ?), y = a(1 + cos ?) at
? = – p/2
Answer
Given:
x = a( ) & y = a(1 + cos ) at
Here, To find , we have to find & and and divide and we get our desired .
(x
n
) = n.x
n – 1
? x = a( )
? = a( ( ) – (sin ))
Page 5
16. Tangents and Normals
Exercise 16.1
1 A. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 4
Answer
Given:
y = at x = 4
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
y =
? y = (
? y =
(x
n
) = n.x
n – 1
The Slope of the tangent is
Since, x = 4
x = 4
=
x = 4
=
x = 4
=
x = 4
= 3
The Slope of the tangent at x = 4 is 3
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 B. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
at x = 9
Answer
Given:
y = at x = 9
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
? y =
? y = (
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = (
Since, x = 9
x = 9
=
x = 9
=
x = 9
=
x = 9
=
x = 9
=
The Slope of the tangent at x = 9 is
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal = – 6
1 C. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
y = x
3
– x at x = 2
Answer
Given:
y = x
3
– x at x = 2
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = x
3
– x
(x
3
) + 3 (x)
= 3.x
3 – 1
– 1.x
1 – 0
= 3x
2
– 1
Since, x = 2
x = 2
= 3 (2)
2
– 1
x = 2
= (3 4) – 1
x = 2
= 12 – 1
x = 2
= 11
The Slope of the tangent at x = 2 is 11
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 D. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
y = 2x
2
+ 3 sin x at x = 0
Answer
Given:
y = 2x
2
+ 3sinx at x = 0
First, we have to find of given function, f(x),i.e, to find the derivative of f(x)
(x
n
) = n.x
n – 1
The Slope of the tangent is
? y = 2x
2
+ 3sinx
=
2 (x
2
) + 3 (sinx)
= 2 2x
2 – 1
+ 3 (cosx)
(sinx) = cosx
= 4x + 3cosx
Since, x = 2
?
x = 0
= 4 0 + 3cos(0)
cos(0) = 1
?
x = 0
= 0 + 3 1
?
x = 0
= 3
The Slope of the tangent at x = 0 is 3
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
1 E. Question
Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
x = a (? – sin ?), y = a(1 + cos ?) at
? = – p/2
Answer
Given:
x = a( ) & y = a(1 + cos ) at
Here, To find , we have to find & and and divide and we get our desired .
(x
n
) = n.x
n – 1
? x = a( )
? = a( ( ) – (sin ))
? = a(1 – ) ...(1)
(sinx) = cosx
? y = a(1 + cos )
? = a( ( ) + (cos ))
(cosx) = – sinx
(Constant) = 0
? = a( + ( – sin ))
? = a( – sin )
? = – asin ...(2)
?
?
The Slope of the tangent is
Since,
?
sin( ) = 1
cos( ) = 0
?
?
? = 1
The Slope of the tangent at x = is 1
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal =
? The Slope of the normal = – 1
1 F. Question
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