n the diagram, four circles of radius 1 with centres $P$, $Q$, $R$, and $S$ are tangent to one another and to the sides of $\triangle ABC$, as shown. The radius of the circle with center $R$ is decreased so that the circle with center $R$ remains tangent to $BC$, the circle with center $R$ remains tangent to the other three circles, and the circle with center $P$ becomes tangent to the other three circles. The radii and tangencies of the other three circles stay the same. This changes the size and shape of $\triangle ABC$. $r$ is the new radius of the circle with center $R$. $r$ is of the form $\frac{a \sqrt{b}}{c}$. Find $a b c$.