apply a sum or defference identity to find the exact function value of cos(13pi/12)

Answer 1

Step 1:

The trigonometric function is .

Rewrite the trigonometric function is

Simplify the function.

Fundamental trigonometric identities: .

Rewrite the trigonometric function is

Addition formula for trigonometric identity is .

Substitute and in the trigonometric formula.

Solution :

The value of trigonometric function is