When I write A_n it means A "sub" n.
a) Define A_n= integral from 2pi to 0 of (Cos(theta))^(2n).d(theta)
Proove the recurrence formula(*):
b) Compute A_0 and derive,using (*), the formula for A_n. (remember the integrals there are from 0 to Pi/2, not 2pi.)
Curls are investigated using Green's theorem.