MathNet 2017-part-04 — 176 problems (EN–VI) Question 113

The segments $A P$ and $A Q$ are tangent to circle $O$ at points $P$ and $Q$, respectively. Moreover, $Q E$ is perpendicular to diameter $P D$ of length $4$. If $P E = 3.6$ and $A P = 6$, what is the length of $Q E$?