Trigonometry Examples

$\cos (a - b)$

Step 1

Use the difference formula for cosine to simplify the expression. The formula states that $\cos (A - B) = \cos (A) \cos (B) + \sin (A) \sin (B)$ .

$\cos (a) \cdot \cos (b) + \sin (a) \cdot \sin (b)$

Step 2

Remove parentheses.

$\cos (a) \cdot \cos (b) + \sin (a) \cdot \sin (b)$