Question

In triangle ABC, angle ACD is the exterior angle measuring 120 degree . If angle B equal to 30 degree, find angle A and angle ACB

Answer 1

Angle A+ angle B=angle ACD( exterior angle property)

=>Angle A+30°=120°

=>Angle A=120°-30°

=>Angle A=90°

Now,

Angle ACD+ Angle ACB=180°(linear pair)

=>120°+Angle ACB=180°

=>Angle ACB=180°-120°

=>Angle ACB=60°