# Expand Using Sum divide Difference Formulas cos(forty minus five)

Expand Using Sum/Difference Formulas cos(45)
The angle is an angle where the values of the six trigonometric functions are known. Because this is the case, Sum to keep the value the same.
Use the sum formula for cosine to Clarify 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 .
Clarify each term.
First, multiply by .
First, multiply by .