Question

in this question we have to prove angle C =90 degree
please explain
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Answer 1

Answer:

we can prove it using the fact that both the triangles are isosceles

Answer 2

Answer:

Given :- ∆ABC is an isosceles triangle in which AB=AC , AB=AD

Prove:- BCD is a right angle

Proof :- In ∆ABC

If AB= AC (equation 1)

In ∆ADC

AD=AC [ AB=AC & AB=AD]

ADC= ACD ( equation 2)

ADC= ABC

+

ADC=ACD

ACB+ACD = ABC + ADC

BCD= ABC + ADC ( equation 3)

In ∆BDC

BDC+ BCD+ CBD= 180°

or

ABC + ADC + BCD = 180°

BCD + BCD = 180°

2 BCD = 180°

BCD = 180÷2 = 90°

BCD = 90°