Two adjacent angles of a parallelogram are equal.

Let the required angle be $x^{\circ}$.

As the adjacent angles are equal, we have:

$x+x=180 \quad\left(s\right.$ ince the sum of adjacent angles of a parallelogram is $\left.180^{\circ}\right)$

$\Rightarrow 2 x=180$

$\Rightarrow x=\frac{180}{2}$

$\Rightarrow x=90^{\circ}$

Hence, the measure of each of the angles is $90^{\circ}$.