Using coterminal angles to evaluate the trigonometric function cosine

The video tutorial explains coterminal angles, focusing on finding the smallest coterminal angle by adding or subtracting multiples of 2π. It demonstrates simplifying angles using revolutions and calculating coterminal angles with examples. The tutorial also covers finding positive angles and using the unit circle, concluding with a cosine calculation of the angle.

How do you convert a negative coterminal angle to a positive one?

What is the cosine value of the angle π/2, and why is it significant?