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Triangle ABC is AN isosceles Triangle in which AB=AC. Side BA is produced to D such that AD=AB. Prove that Angle BCD = 90 Degree

AD = AB THIS GIVEN .

AB = AC THIS ALSO GIVEN.

THEREFORE AD=AC.

THEREFORE ANGLE ABC=ACB AND ANGLE ADC= ACD

TAKE ANGLE ABC = X

THEREFORE ANGLE ACB = X

TAKE ANGLE ADC = Y

THEREFORE ANGLE ACD = Y

2X + 2Y= 180( ANGLE SUM PROPERTY)

THEREFORE X+Y= 90

HENCE PROVED ANGLE BCD = 90