ABB' is isosceles triangle and points O1 and O2 are on line AM (M=midpoint of BB'). Circle O1 is tangented to BB', O2 is tangented to AB and AB'. Their common tangent lines pass through B or B'. Diameter ratio (O2/O1) = length ratio (PR/QP).
Draw two circles using only compass and ruler. You can move point P and B.