1. In parallelograms $A B C D$ and $A E F D$, heights $B P=7$ and $F Q=10$ are drawn to the side $A D$. Find the length of the perpendicular from point $C$ to $E F$. If there are multiple possible values, list them in any order separated by a semicolon.
Answer: $3 ; 17 \| 17 ; 3$