Common Segment Products for Circles

The diameter of a circle is a line segment that stretches from 1 point on the circumference of a circle to the opposite side. However, a chord can be from any 2 points on a circles' circumference.

Chords $AB$ and $CD$ intersect at $P$. If $AP=4$, $BP=5$, and $CP=7$, find $DP$.