Evaluate the half angle formula for cosine

The video tutorial explains the cosine half-angle formula, focusing on determining the value of U when 75 degrees equals U/2. It discusses the importance of quadrant determination for sign selection and uses reference angles to simplify expressions. The tutorial concludes with a final simplification of the expression.

What is the reference angle for 150 degrees, and how does it relate to the cosine value?

How do you simplify the expression involving the square root in the final steps of the problem?