Ok, transforming the first part of the Hann window, I've got

F(k)=0.5 (delta(k) + 0.5 (delta (k-2pi/T) + delta (k+2pi/T).

and for the rectangular window I have

W(k)= (sin(0.5kT))\k

Am I right in thinking that the convolution of the two is

S(k)= 0.5 ((sin(0.5kT))\k + 0.5 ((sin (0.5 (k-2pi/T))) + (sin (0.5 (k+2pi/T)))))?

Would this then make the transform of the window multiplied by cos (2pi/T)x

0.5(S(k-2pi/T) + (S(k+2pi/T))?

Thanks ever so much for your help, and sorry about the mess- I've tried to make things as clear as possible, but I don't know how to input mathematical symbols on here...

Thanks