14. Convert 15 to radians. 15. Convert -7n 6 to degrees. In what quadrant does this angle lie? 16. Evaluate esc(-97/4). 17. Find all o in the interval [0, 2x] that satisfy cos 0 = -V3 sing. 18. Graph y = 3sin (x - [) + 1 over the interval [0, 2x]. 19. Find the derivatives. (a) f(x) = sin(x3 + x?) (b) f(x) = cos r (c) f(x) = \\tan(5x + 1) (d) f(x) = 13 cos _ (e) f(x) _ It sinc 1 - cosr 20. The formula for determining the amount of sales (S in Sthousands per month) is given by: S = 74.5 + 3 sin 6 (where t = 1 corresponds to the beginning of March). (a) Determine the rate of change of sales in June. State what it predicts. (b) Graph the function. Find the month with the maximum sales