Find Fourier cosine transform of exp(-a²x²) and hense evaluate Fourier sine transform of x.exp(-a²x²)

plz help me..

i can solve this ques. only if there is x instead of x² in the exponential function exp(-a²x²). bcoz in this situation i can use integral formula :- ⌠exp(-ax)cos(sx)dx = exp(-ax)/a²+x²[bsin(sx)-acos(sx)] but what should i do if there is x² in exponential function exp.??