I need help for this two question.

3. Consider the half cosine pulse (t) defined as x(t)= cos(2nf,t). -T/2stsT/2 0. else a) Find the Fourier Transform of the half cosine pulse (Hint: Use the multiplication property). b) What happens to the spectrum as T goes to infinity? 4. Use the convolution property to derive the Fourier Transform of the signal for the -TSIST x(t) = T 0, elsewhere