Half angle of cosine given angle in degrees

The video tutorial covers the calculation of the cosine of 105 degrees using the half-angle formula. It explains the importance of determining the correct sign based on the quadrant and demonstrates how to simplify complex fractions. The tutorial emphasizes understanding when to use plus or minus in trigonometric formulas and provides a step-by-step approach to applying these concepts.

What is the cosine formula for the half angle?

Explain the significance of the plus or minus in the half angle formula.

In which quadrant is 105 degrees located, and how does that affect the cosine value?

What is the reference angle for 210 degrees, and how does it relate to the cosine value?

How do you simplify a complex fraction under a radical?