Alternate Angles Test

Ray $PQ$ and ray $PR$ are perpendicular to each other. Points $B$ and $A$ are in the interior and exterior of $\angle QPR$ respectively. Ray $PB$ and ray $PA$ are perpendicular to each other. Draw a figure showing all these rays and write a pair of congruent angles.

Ray $PQ$ and ray $PR$ are perpendicular to each other. Points $B$ and $A$ are in the interior and exterior of $\angle QPR$ respectively. Ray $PB$ and ray $PA$ are perpendicular to each other. Draw a figure showing all these rays and write a pair of supplementary angles

Prove that, if a line is perpendicular to one of the two parallel lines, then it is perpendicular to the other line.