Use reference angles, the unit circle, and the fact that
Draw a unit circle diagram for the given angle.Unit circle, with right triangle in first quadrant, labeled as follows: hypotenuse, 1, horizontal leg, 1 half, angle opposite vertical leg, pi thirds.
Reflect the triangle in each of the 4 quadrants. Quadrant 2 is shown for you. Added to the unit circle, a right triangle in second quadrant, labeled as follows: hypotenuse, 1, horizontal leg, negative 1 half.