9π/2 is the same angle as π/2 (since 9π/2 = π/2+4π)
we all know that the co- in cosine means "complementary angle" so
cos(π/2-θ) = sinθ
Or, you can use the difference of angles formula. Same result.
Write the expression as a trigonometric function of only θ, and use a graphing utility to confirm your answer graphically.
cos((9π/2)-θ
1 answer
1 answer