Question

An exterior angle of ∆ABC is Angle ACD . Prove that Angle A + Angle B = Angle ACD.






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Answer 1

Answer:

Step-by-step explanation:

An exterior angle of a triangle is equal to the sum of its interior opposite angles.

Consider triangle ABC. ACD is an exterior angle.

Through C, draw CE||BA

To prove:  1 + 2 =  ACD

Proof: 1 = x (pair of alternate interior angles since, CE||BA)

2 = y (pair of corresponding angles)

1 + 2 = x + y

i.e. 1 + 2 = ACD [  x + y = ACD]

Hence proved.