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CBSE Class 9 Answered

ABC is an isosceles triangle in which AB = AC. Side BA is produced to D such that AD = AB. Show that BCD is a right angle.
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
answered-by-expert Expert Answer

Given: ABC is an isosceles triangle in which AB = BC

BA is produced to D such that AB = AD

To prove: BCD = 90o

Proof: In ABC

AB = AC

1 = 2 … (i)

Similarly, 3 = 4 … (ii)

In BCD, by angle sum property,

1 + (2 + 3) + 4 = 180o

2 + (2 + 3) + 3 = 180o

2(2 + 3) = 180o

2 + 3 = 90o

BCD = 90o

Answered by | 04 Jun, 2014, 03:23: PM

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