Two tangents $\overline{PA}$ and $\overline{PB}$ are drawn to a circle, where $P$ lies outside the circle, and $A$ and $B$ lie on the circle. The length of $\overline{PA}$ is $2,$ and the circle has a radius of $2.$ Find the length $AB.$
The length AB is 4*sqrt(7).
+1911 
