Question 173
Consider the rectangle $ABCD$ and the arbitrary points $E \in (CD)$ and $F \in (AD)$. The perpendicular line from $E$ on the line $FB$ intersects $BC$ in $P$. The perpendicular line from $F$ on the line $EB$ intersects $AB$ in $Q$. Show that the points $P, D$ and $Q$ are collinear.