Page 1
Question:1
In the given figure, AB || CD and O is the midpoint of AD.
Show that
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Solution:
Given: In the given figure, AB || CD and O is the midpoint of AD.
To prove:
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Proof:
i
In ?AOB and ?DOC,
?BAO = ?CDO (Alternate interior angles, AB || CD)
AO = DO (Given, O is the midpoint of AD)
?AOB = ?DOC Verticallyoppositeangles
? By ASA congruence criteria,
?AOB ? ?DOC
ii
? ?AOB ? ?DOC
From(i)
? BO = CO CPCT
Hence, O is the midpoint of BC.
Question:2
In the given figure, AD and BC are equal perpendiculars to a line segment AB. Show that CD bisects AB.
Solution:
Given: In the given figure, AD and BC are equal perpendiculars to a line segment AB.
To prove: CD bisects AB
Proof:
In ?AOD and ?BOC,
?DAO = ?CBO = 90
°
Page 2
Question:1
In the given figure, AB || CD and O is the midpoint of AD.
Show that
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Solution:
Given: In the given figure, AB || CD and O is the midpoint of AD.
To prove:
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Proof:
i
In ?AOB and ?DOC,
?BAO = ?CDO (Alternate interior angles, AB || CD)
AO = DO (Given, O is the midpoint of AD)
?AOB = ?DOC Verticallyoppositeangles
? By ASA congruence criteria,
?AOB ? ?DOC
ii
? ?AOB ? ?DOC
From(i)
? BO = CO CPCT
Hence, O is the midpoint of BC.
Question:2
In the given figure, AD and BC are equal perpendiculars to a line segment AB. Show that CD bisects AB.
Solution:
Given: In the given figure, AD and BC are equal perpendiculars to a line segment AB.
To prove: CD bisects AB
Proof:
In ?AOD and ?BOC,
?DAO = ?CBO = 90
°
Given
AD = BC
Given
?DOA = ?COB
Verticallyoppositeangles
? By AAS congruence criteria,
?AOD ? ?BOC
? AO = BO
CPCT
Hence, CD bisects AB.
Question:3
In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
Show that ?ABC ? ?CDA.
Solution:
Given: In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
To prove: ?ABC ? ?CDA
Proof:
In ?ABC and ?CDA,
?
BAC = ?
DCA (Alternate interior angles, p ?
q)
?
BCA = ?
DAC (Alternate interior angles, l ?
m)
AC = CA Commonside
?
By ASA congruence criteria,
?ABC ? ?CDA
Question:4
AD is an altitude of an isosceles ?ABC in which AB = AC.
Show that i
AD bisects BC, ii
AD bisects ?A.
Solution:
Given: AD is an altitude of an isosceles ?ABC in which AB = AC.
To prove: i
AD bisects BC, ii
AD bisects ?A
Page 3
Question:1
In the given figure, AB || CD and O is the midpoint of AD.
Show that
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Solution:
Given: In the given figure, AB || CD and O is the midpoint of AD.
To prove:
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Proof:
i
In ?AOB and ?DOC,
?BAO = ?CDO (Alternate interior angles, AB || CD)
AO = DO (Given, O is the midpoint of AD)
?AOB = ?DOC Verticallyoppositeangles
? By ASA congruence criteria,
?AOB ? ?DOC
ii
? ?AOB ? ?DOC
From(i)
? BO = CO CPCT
Hence, O is the midpoint of BC.
Question:2
In the given figure, AD and BC are equal perpendiculars to a line segment AB. Show that CD bisects AB.
Solution:
Given: In the given figure, AD and BC are equal perpendiculars to a line segment AB.
To prove: CD bisects AB
Proof:
In ?AOD and ?BOC,
?DAO = ?CBO = 90
°
Given
AD = BC
Given
?DOA = ?COB
Verticallyoppositeangles
? By AAS congruence criteria,
?AOD ? ?BOC
? AO = BO
CPCT
Hence, CD bisects AB.
Question:3
In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
Show that ?ABC ? ?CDA.
Solution:
Given: In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
To prove: ?ABC ? ?CDA
Proof:
In ?ABC and ?CDA,
?
BAC = ?
DCA (Alternate interior angles, p ?
q)
?
BCA = ?
DAC (Alternate interior angles, l ?
m)
AC = CA Commonside
?
By ASA congruence criteria,
?ABC ? ?CDA
Question:4
AD is an altitude of an isosceles ?ABC in which AB = AC.
Show that i
AD bisects BC, ii
AD bisects ?A.
Solution:
Given: AD is an altitude of an isosceles ?ABC in which AB = AC.
To prove: i
AD bisects BC, ii
AD bisects ?A
Proof:
i
In ?ABD and ?ACD,
?
ADB = ?
ADC = 90°
(Given, AD ?
BC)
AB = AC Given
AD = AD Commonside
?
By RHS congruence criteria,
?ABD ? ?ACD
?
BD = CD CPCT
Hence, AD bisects BC.
ii
?
?ABD ? ?ACD
From(i)
?
?
BAD = ?
CAD CPCT
Hence, AD bisects ?A.
Question:5
In the given figure, BE and CF are two equal altitudes of ?ABC.
Show that i
?ABE ? ?ACF, ii
AB = AC.
Solution:
In ? ABE and ? ACF, we have: BE = CF (Given) ?BEA = ?CFA = 90° ?A = ?A (Common) ? ABE ? ? ACF (AAS criterion)
AB = AC CPCT
Question:6
?ABC and ?DBC are two isosceles triangles on the same base BC and vertices A and D are on the same side of BC. If AD is extended to intersect BC at E, show that
i
?ABD ? ?ACD
ii
?ABE ? ?ACE
iii
AE bisects ?A as well as ?D
iv
AE is the perpendicular bisector of BC.
Solution:
Given: ?ABC and ?DBC are two isosceles triangles on the same base BC.
To prove:
i
?ABD ? ?ACD
ii
?ABE ? ?ACE
Page 4
Question:1
In the given figure, AB || CD and O is the midpoint of AD.
Show that
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Solution:
Given: In the given figure, AB || CD and O is the midpoint of AD.
To prove:
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Proof:
i
In ?AOB and ?DOC,
?BAO = ?CDO (Alternate interior angles, AB || CD)
AO = DO (Given, O is the midpoint of AD)
?AOB = ?DOC Verticallyoppositeangles
? By ASA congruence criteria,
?AOB ? ?DOC
ii
? ?AOB ? ?DOC
From(i)
? BO = CO CPCT
Hence, O is the midpoint of BC.
Question:2
In the given figure, AD and BC are equal perpendiculars to a line segment AB. Show that CD bisects AB.
Solution:
Given: In the given figure, AD and BC are equal perpendiculars to a line segment AB.
To prove: CD bisects AB
Proof:
In ?AOD and ?BOC,
?DAO = ?CBO = 90
°
Given
AD = BC
Given
?DOA = ?COB
Verticallyoppositeangles
? By AAS congruence criteria,
?AOD ? ?BOC
? AO = BO
CPCT
Hence, CD bisects AB.
Question:3
In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
Show that ?ABC ? ?CDA.
Solution:
Given: In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
To prove: ?ABC ? ?CDA
Proof:
In ?ABC and ?CDA,
?
BAC = ?
DCA (Alternate interior angles, p ?
q)
?
BCA = ?
DAC (Alternate interior angles, l ?
m)
AC = CA Commonside
?
By ASA congruence criteria,
?ABC ? ?CDA
Question:4
AD is an altitude of an isosceles ?ABC in which AB = AC.
Show that i
AD bisects BC, ii
AD bisects ?A.
Solution:
Given: AD is an altitude of an isosceles ?ABC in which AB = AC.
To prove: i
AD bisects BC, ii
AD bisects ?A
Proof:
i
In ?ABD and ?ACD,
?
ADB = ?
ADC = 90°
(Given, AD ?
BC)
AB = AC Given
AD = AD Commonside
?
By RHS congruence criteria,
?ABD ? ?ACD
?
BD = CD CPCT
Hence, AD bisects BC.
ii
?
?ABD ? ?ACD
From(i)
?
?
BAD = ?
CAD CPCT
Hence, AD bisects ?A.
Question:5
In the given figure, BE and CF are two equal altitudes of ?ABC.
Show that i
?ABE ? ?ACF, ii
AB = AC.
Solution:
In ? ABE and ? ACF, we have: BE = CF (Given) ?BEA = ?CFA = 90° ?A = ?A (Common) ? ABE ? ? ACF (AAS criterion)
AB = AC CPCT
Question:6
?ABC and ?DBC are two isosceles triangles on the same base BC and vertices A and D are on the same side of BC. If AD is extended to intersect BC at E, show that
i
?ABD ? ?ACD
ii
?ABE ? ?ACE
iii
AE bisects ?A as well as ?D
iv
AE is the perpendicular bisector of BC.
Solution:
Given: ?ABC and ?DBC are two isosceles triangles on the same base BC.
To prove:
i
?ABD ? ?ACD
ii
?ABE ? ?ACE
iii
AE bisects ?A as well as ?D
iv
AE is the perpendicular bisector of BC
Proof:
i
In ?ABD and ?ACD,
BD = CD (Given, ?DBC is an isosceles triangles)
AB = AC (Given, ?ABC is an isosceles triangles)
AD = AD Commonside
?
By SSS congruence criteria,
?ABD ? ?ACD
Also, ?
BAD = ?
CAD CPCT
or, ?
BAE = ?
CAE .....1
ii
In ?ABE and ?ACE,
AB = AC (Given, ?ABC is an isosceles triangles)
?
BAE = ?
CAE
From(i)
AE = AE Commonside
?
By SAS congruence criteria,
?ABE ? ?ACE
Also, BE = CE CPCT
.....2
And, ?
AEB = ?
AEC CPCT
.....3
iii
In ?BED and ?CED,
BD = CD (Given, ?DBC is an isosceles triangles)
BE = CE
From(2)
DE = DE Commonside
?
By SSS congruence criteria,
?BED ? ?CED
Also, ?
BDE = ?
CDE CPCT
.....4
iv
?
?
BAE = ?
CAE
From(1)
And, ?
BDE = ?
CDE
From(4)
?
AE bisects ?A as well as ?D.
v
Page 5
Question:1
In the given figure, AB || CD and O is the midpoint of AD.
Show that
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Solution:
Given: In the given figure, AB || CD and O is the midpoint of AD.
To prove:
i
?AOB ? ?DOC.
ii
O is the midpoint of BC.
Proof:
i
In ?AOB and ?DOC,
?BAO = ?CDO (Alternate interior angles, AB || CD)
AO = DO (Given, O is the midpoint of AD)
?AOB = ?DOC Verticallyoppositeangles
? By ASA congruence criteria,
?AOB ? ?DOC
ii
? ?AOB ? ?DOC
From(i)
? BO = CO CPCT
Hence, O is the midpoint of BC.
Question:2
In the given figure, AD and BC are equal perpendiculars to a line segment AB. Show that CD bisects AB.
Solution:
Given: In the given figure, AD and BC are equal perpendiculars to a line segment AB.
To prove: CD bisects AB
Proof:
In ?AOD and ?BOC,
?DAO = ?CBO = 90
°
Given
AD = BC
Given
?DOA = ?COB
Verticallyoppositeangles
? By AAS congruence criteria,
?AOD ? ?BOC
? AO = BO
CPCT
Hence, CD bisects AB.
Question:3
In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
Show that ?ABC ? ?CDA.
Solution:
Given: In the given figure, two parallel line l and m are intersected by two parallel lines p and q.
To prove: ?ABC ? ?CDA
Proof:
In ?ABC and ?CDA,
?
BAC = ?
DCA (Alternate interior angles, p ?
q)
?
BCA = ?
DAC (Alternate interior angles, l ?
m)
AC = CA Commonside
?
By ASA congruence criteria,
?ABC ? ?CDA
Question:4
AD is an altitude of an isosceles ?ABC in which AB = AC.
Show that i
AD bisects BC, ii
AD bisects ?A.
Solution:
Given: AD is an altitude of an isosceles ?ABC in which AB = AC.
To prove: i
AD bisects BC, ii
AD bisects ?A
Proof:
i
In ?ABD and ?ACD,
?
ADB = ?
ADC = 90°
(Given, AD ?
BC)
AB = AC Given
AD = AD Commonside
?
By RHS congruence criteria,
?ABD ? ?ACD
?
BD = CD CPCT
Hence, AD bisects BC.
ii
?
?ABD ? ?ACD
From(i)
?
?
BAD = ?
CAD CPCT
Hence, AD bisects ?A.
Question:5
In the given figure, BE and CF are two equal altitudes of ?ABC.
Show that i
?ABE ? ?ACF, ii
AB = AC.
Solution:
In ? ABE and ? ACF, we have: BE = CF (Given) ?BEA = ?CFA = 90° ?A = ?A (Common) ? ABE ? ? ACF (AAS criterion)
AB = AC CPCT
Question:6
?ABC and ?DBC are two isosceles triangles on the same base BC and vertices A and D are on the same side of BC. If AD is extended to intersect BC at E, show that
i
?ABD ? ?ACD
ii
?ABE ? ?ACE
iii
AE bisects ?A as well as ?D
iv
AE is the perpendicular bisector of BC.
Solution:
Given: ?ABC and ?DBC are two isosceles triangles on the same base BC.
To prove:
i
?ABD ? ?ACD
ii
?ABE ? ?ACE
iii
AE bisects ?A as well as ?D
iv
AE is the perpendicular bisector of BC
Proof:
i
In ?ABD and ?ACD,
BD = CD (Given, ?DBC is an isosceles triangles)
AB = AC (Given, ?ABC is an isosceles triangles)
AD = AD Commonside
?
By SSS congruence criteria,
?ABD ? ?ACD
Also, ?
BAD = ?
CAD CPCT
or, ?
BAE = ?
CAE .....1
ii
In ?ABE and ?ACE,
AB = AC (Given, ?ABC is an isosceles triangles)
?
BAE = ?
CAE
From(i)
AE = AE Commonside
?
By SAS congruence criteria,
?ABE ? ?ACE
Also, BE = CE CPCT
.....2
And, ?
AEB = ?
AEC CPCT
.....3
iii
In ?BED and ?CED,
BD = CD (Given, ?DBC is an isosceles triangles)
BE = CE
From(2)
DE = DE Commonside
?
By SSS congruence criteria,
?BED ? ?CED
Also, ?
BDE = ?
CDE CPCT
.....4
iv
?
?
BAE = ?
CAE
From(1)
And, ?
BDE = ?
CDE
From(4)
?
AE bisects ?A as well as ?D.
v
? ?AEB + ?AEC = 180° (Linear pair) ? ?AEB + ?AEB = 180° [From (3)] ? 2 ?AEB = 180° ? ?AEB =
180°
2
? ?AEB = 90° . . . . . (5)
From 2
and 5
, we get
AE is the perpendicular bisector of BC.
Question:7
In the given figure, if x = y and AB = CB, then prove that AE = CD.
Solution:
Consider the triangles AEB and CDB.
?EBA = ?DBC
Commonangle
...i
Further, we have:
?BEA = 180 -y ?BDC = 180 -xSince x = y, we have: 180 -x = 180 -y ? ?BEA = ?BDC . . . (ii)
AB = CB Given
...iii
From i
, ii
and iii
, we have:
? BDC ? ? BEA
AAScriterion
? AE = CD CPCT
Hence, proved.
Question:8
In the given figure, line l is the bisector of an angle ?A and B is any point on l. If BP and BQ are perpendiculars from B to the arms of ?A, show that
i
?APB ? ?AQB
ii
BP = BQ, i.e., B is equidistant from the arms of ?A.
Solution:
Given: In the given figure, ?BAQ = ?BAP, BP ?
AP and BQ ?
AQ.
To prove:
i
?APB ? ?AQB
ii
BP = BQ, i.e., B is equidistant from the arms of ?A.
Proof:
i
In ?APB and ?AQB,
?BAQ = ?BAP, Given
?APB = ?AQB = 90°
(Given, BP ?
AP and BQ ?
AQ)
AB = AB Commonside
Read More