Rewrite the products into sums or the sums into products. \text { 1) }-3 \sin 8 A \cos 2 A \text { 2) }-5 \cos 7 B \cos 3 B

\begin{aligned} &\text { 3) } \tan \theta=-\frac{15}{8} \text { where } \frac{3 \pi}{2} \leq \theta<2 \pi\\ &\text { Find } \sin \frac{\theta}{2} \end{aligned} \text { 3) } \sin 7 \theta \cos 3 \theta \text { 4) } \cos 16 \theta+\cos 4 \theta \text { 5) } \sin 5 A+\sin 3 A \text { 6) } \cos 20 B-\cos 4 B