an isosceles triangle abc, with ab=ac, the bisectors of angle b and c intersect each other at o. join a to o. show that a) ob=oc b) ao bisects angle a
Answers
Answer:
(i) In △ABC, we have
AB=AC
⇒∠C=∠B ∣ Since angles opposite to equal sides are equal
⇒
2
1
∠B=
2
1
∠C
⇒∠OBC=∠OCB
⇒∠ABO=∠ACO …(1)
⇒OB=OC ∣ Since sides opp. to equal ∠s are equal …(2)
(ii) Now, in △ABO and △ACO, we have
AB=AC ∣ Given
∠ABO=∠ACO ∣ From (1)
OB=OC ∣ From (2)
∴ By SAS criterion of congruence, we have
△ABO≅△ACO
⇒∠BAO=∠CAO ∣ Since corresponding parts of congruent triangles are equal
⇒ AO bisects ∠A
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Step-by-step explanation:
Solution:-
Given:-
AB = AC and
the bisectors of B and C intersect each other at O
(i) Since ABC is an isosceles with AB = AC,
B = C
½ B = ½ C
⇒ OBC = OCB (Angle bisectors)
∴ OB = OC (Side opposite to the equal angles are equal.)
(ii) In ΔAOB and ΔAOC,
AB = AC (Given in the question)
AO = AO (Common arm)
OB = OC (As Proved Already)
So, ΔAOB ΔAOC by SSS congruence condition.
BAO = CAO (by CPCT)
Thus, AO bisects A.