Evaluate the arc cosine without a calculator

The video tutorial explains how to find the angle whose cosine is -1/2 using the unit circle. It identifies the coordinate points on the unit circle where the cosine is -1/2 and determines the angles corresponding to these points. The tutorial also discusses the restrictions on cosine values and concludes with the correct angle within the specified range.

Explain the restrictions on the cosine function and how they affect the angle selection.

What is the only angle between 0 and π that corresponds to the cosine of -1/2?