3. (4 points) Suppose that cot 0 = 3 and o lies in the third quadrant. Find the exact value of cos(20) 4. (4 points) Find the exact value of sin 75 . sin 15, by using a product-to-sum identity. Show your step-by-step work. Decimal answers will not earn credit. 5. (4 points total) Circle the best answer (1 point) and include supporting algebraic work (3 points). 8 sinta is equivalent to which of the following expressions? Hint: Use a power-reducing identity to rewrite the expression 8 sin a so that it does not contain any powers of trig functions greater than 1. (a) 3 - 3 cos(2:) (b) 3 - 4 cos(2x) + cos(4:) (c) 2 - 2 cos(2x) + cos(4:) (d) none of the above