How would I solve the following question?
Show that
$2\sin(127.5)\sin(97.5)=(\sqrt{3}+\sqrt{2})/2$
My work is I know
$\sin A\sin B=(-1/2)(\cos(A+B)-\cos(A-B))$
So I did
$(-1/2)(\cos(127.5+97.5)-\cos(127.5-97.5))$
but I do not get the correct answer.