Answer:
[tex]90^{\circ}[/tex]. In other words, these two angles are both right angles, and this parallelogram would be a rectangle.
Step-by-step explanation:
Two angles that congruent have the same size.
At the same time, those two adjacent angles of this parallelogram would be a pair of consecutive interior angles. Because the two sides of a parallelogram are parallel to one another, the sum of these two consecutive interior angles would be [tex]180^{\circ}[/tex]- they are supplementary to one another.
Let the two angles be [tex]\angle1[/tex] and [tex]\angle 2[/tex].
[tex]\angle 1 = \angle 2[/tex] because the two angles are congruent.
[tex]\angle 1 + \angle 2 = 180^{\circ}[/tex] because these two angles are adjacent angles of a parallelogram.
Hence, [tex]\displaystyle \angle 1 = \angle 2 = \frac{1}{2} \times 180{^\circ} = 90^{\circ}[/tex].
