Question

Side BC of a triangle ABC has been produced to a point D such that ∠ACD = 1200. If ∠B = ½ ∠A, then ∠A =?

Answer 1

Answer:

∠A= 80°

Step-by-step explanation:

∠ACD is the exterior angle, hence it is equal to sum of internal opposite angles

Therefore

∠ACD = ∠A+ ∠B

Also given

∠A= 2∠B

Therefore

120°= 2∠B+ ∠B= 3∠B

Hence ∠B=40°

And ∠A= 80°