Answers

2014-09-23T20:28:30+05:30
In triangle ABC, AB = AC is given
angle ABC= angle ACB (opposite angles are equal in triangle)
in another triangle AD=AC
angle ACD= angle ADC (opposite angles are equal in triangle)
In triangle BCD,
 angle ABC + angle BCD + angle ADC = 180 degrees
angle ACB+angle ACB+angle ACD+angle ACD = 180 degrees
2 (angle ACB+angle ACD) = 180 degrees
2(angle BCD) = 180 degrees
angle BCD is 180/2 = 90 degrees.
Hence, proved.

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