Trapezoid $ABCD$ is inscribed in the semicircle with diameter $\overline{AB}$, as shown below. If $CD = 7$, $AD = 3$, and $BC = 3$, then find the radius of the semicircle.
I tried and searched but nothing was correct
The radius of the semicircle is $\frac{\sqrt{85}}{2}$.
+195 
