A refracting telescope is $36.4 \mathrm{cm}$ long and has a $6.0 \mathrm{cm}$ diameter aperture. The magnifying power is $90.0 .$
(a) What are the focal lengths of the lenses?
(b) What is the diffraction limit on the minimum angular separation of objects that the telescope can resolve in $500 \mathrm{nm}$ light?