Please answer with steps for a better understanding. Use exact solutions aka rational expressions.

1. Find the exact value of cos(pi/ 3 +pi/4) by using trigonometric identities to rewrite and simplify.

2. Use trigonometric identities and algebra to find exact solutions tan(x +)cos(x + pi/2) = 0. Give all

solutions on the interval [0,2].

3. Given that sinA=3/7, cosB=2/5, and that both A and B are in quadrant II, find cos(AB). Simplify it to a single value, leaving it in the form of a rational number.

4. Verify the identity sin(A B)sin(A + B) = sin&2 A sin^2 B .