The easiest angle to find is v=3 in the first quadrant. When we draw the unit circle, we see that the angle which makes the same angle with the positive x-axis as v=3, but is under the x-axis, also has a cosine value of 1/2 (same x-coordinate).
There are thus two angles, v=3 and v=2−3=53 which have their cosine value equal to 1/2.
3
