Two adjacent angles of a parallelogram have equal measure. Find the measure of each of the angles of the parallelogram.

Let ABCD be the parallelogram with ∠A = ∠B.

We know: Sum of adjacent angles = 180°

∠A + ∠B = 180º

2∠A = 180º (∠A = ∠B)

∠A = 90º

∠B = ∠A = 90º

∠C = ∠A = 90º (Opposite angles)

∠D = ∠B = 90º (Opposite angles)

Thus, each angle of the parallelogram measures 90º.