Practice!

Sample Problem

Use reference angles to evaluate sin (-10π/3). Round your answer to three decimal places.

Sin (-10π/3)=

Solution

-10π/3 is coterminal with 2π/3 (-10π/3+4π=2π/3). π/2<2π/3<π, 2π/3 is located in Quadrant II.

π-(2π/3)=π/3

sin(π/3)=√3/2=0.866