This can be answered by understanding the unit circle and the Pythagorean theorem. 210° can form a right triangle with the x-axis in quadrant III. To get the value of the angle formed between the circle’s radius and the x-axis, divide the angles of the 2 quadrants from 210°. 210°-90-°90° = 30° In the Pythagorean theorem has a ratio of 1,2, √3 of the sides of the triangle. In a unit circle, the opposite side from the 30° angle is 1. The adjacent side is √3 while the hypotenuse is 2. With this info, we can use SOHCAHTOA. So, Sin(∅) = opposite / hypotenuse Sin(30°) = ½ =0.5 Cos(∅) = adjacent/hypotenuse Cos(30°) = sqrt.3/2 = 0.86602 = 0.87
