Express the following as a multiplicative expression;

For example, for number 6, the answer would simplify to -1 * cos(2a):


1) sin(a - 2π/3) - sin(a + 2π/3)

2) sin(a + b) + sin(a - b)

3) cos(2a - π/16) + cos(9π/16 - 2a)

4) 1 - cos(a)

5) 1 + sin(a)

6) 1 - 2*cos^2(a)

7) sin(4b) + sin(10b) + sin(22b) + sin(16b)