# Trigonometry Examples

First, split the angle into two angles where the values of the six trigonometric functions are known. In this case, can be split into .
Use the sum formula for cosine to simplify the expression. The formula states that .
The exact value of is .
The exact value of is .
The exact value of is .
The exact value of is .
Simplify each term.
Multiply by .
Simplify .
Multiply and .
Combine using the product rule for radicals.
Multiply by .
Multiply by .
Simplify .
Multiply and .
Multiply by .
Combine the numerators over the common denominator.