Question

In parallelogram ABCD, angle D = 115 degree, determine the measure of angle A and angle B

Answer 1

In any parallelogram, opp. angles are congruent and consecutive are supplementary.
The measure of angle A =115 degrees. (as angle A is opp to angle D). and angle B = 180 -115 = 65 degrees. (since the angles are consecutive and hence supplementary)

Answer 2

Since the sum of any two consecutive angles of a parallelogram is 180⁰

Therefore,

∠A+∠D=180⁰and ∠A+∠B=180⁰

Now,

∠A+∠D=180⁰

∠A+115⁰ =180⁰

∠A=65⁰

And,

∠A+∠B=180⁰

65⁰ +∠B=180⁰

∠B=115⁰

Thus, ∠A=65⁰ and ∠B=115⁰