How do you evaluate cos (-15pi/2)? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer Nghi N. Nov 9, 2015 Evaluate cos(−15π2) Ans: 0 Explanation: cos(−15π2)=cos(π2−16π2)=cos(π2−8π)=cos(π2)=0 Answer link Related questions How do you find the trigonometric functions of any angle? What is the reference angle? How do you use the ordered pairs on a unit circle to evaluate a trigonometric function of any angle? What is the reference angle for 140∘? How do you find the value of cot300∘? What is the value of sin−45∘? How do you find the trigonometric functions of values that are greater than 360∘? How do you use the reference angles to find sin210cos330−tan135? How do you know if sin30=sin150? How do you show that (cosθ)(secθ)=1 if θ=π4? See all questions in Trigonometric Functions of Any Angle Impact of this question 6836 views around the world You can reuse this answer Creative Commons License