S and T are the centers of their respective circles . The two circles are mutually tangent at point U . If segment RS = d , what is the radius of the smaller circle in terms of d and ` theta ' -LRB- angle -RRB- ?
When Given two circles with centers O and P , tangent to each other at A and a line tangent to both circles at B and C. Prove angle BAC is 90 degrees ?