5. For each of the following functions y(z), find its Fourier transform y(k), and then

sketch graphs of y(x) and ÿ(k). (In cases where the Fourier transform ỹ(k) is complex,

sketch graphs of its real part and its imaginary part separately.)

(a) y(x) = A cos(kxz), where A and ko are real constants.

(b) y(x) = De-, where D and A are positive real constants.