1. Find the probability of isotropic scattering into a
differential solid angle is d_/4_r2 where the
differential solid angle d_ is given as 2_rsin(_COM)(rd_COM).
[Hint: Integrate over _ to get scattering in the segment]
2. Show that scattering in the COM system is isotropic. For
this purpose, find cos (_ COM) and interpret the result. [Hint:
Multiply the cosine of the scattering angle in the COM by the probability of
scattering and integrate from 0 to _].