Cirangle!

Geometry Level 3

The radius of the circle is $20$ and $\angle AOB=\frac{3}{10} \pi.$

If $C$ is a point on $\overline{BO}$ such that $\overline{AC}$ is the bisector of $\angle BAO,$ what is the length of $\overline{BC}?$

Round your answer to 3 decimal places.