28. What is one identity used in the solution? a. sin2x = 1 - cos2 x b. cos2 x = sin2x - 1 c. sin2 x =1 + cos2x d. cos2x = 1+ sin2 x 29. What is an intermediate step? a. cos x (cos x - 1) = 0 b. sin x (sin x + 1) = 0 C. cos x (cos x + 1) = 0 d. sin x (sin x - 1) = 0 30. What is the solution set? a. TT 2 2 b. IT 3TT (2' 2 C. {0, TT d. O, IT 3TT ' 2' 2 To answer questions 31-33, use this equation: sin _ x = cos x 31. What is one identity used in the solution? a. sin = + 1+ COS X 2 2 b. sin _ 1-cosx 2 2 C. sin _ 1+ cos x 2 2 d. sin- = + 1- COS X 2 2 Unit 4 Evaluation M 32. What is an intermediate step? a. (2 cos x + 1) (cos x + 1) = 0 b. (2 cos x + 1) (cos x - 1) = 0 c. (2 cos x - 1) (cos x + 1) = 0 d. (2 cos x - 1) (cos x - 1) = 0 33. What is the solution set? a. JO, IT 2TT ' 3' 3 b . IT 5TT 3' 3 C . TT 2TT 3' 3 d. TT 13 3