a) Evaluate sin (−210° ) = ________ b) Evaluate cos (10π4) = _______

Question

Use the / symbol for a fraction bar if needed.

a) Evaluate sin (-210°) = 

b) Evaluate cos (10π/4) = 

Answer 1

sin(-210) = -1/2

-210 has a reference angle of 30 degrees, in quadrant III. sines are negative in the 3rd quadrant.

cos(10pi/4) = 0

10pi/4 = 5pi/2 = 5(90) = 450 degrees which has a reference angle of 450-360 = 90 degrees. cos(90) = 0