Answer
Subtraction
$cos(x - y)= cos\ x\ cos\ y + sin\ x\ sin\ y$
Work Step by Step
If we know the values of the sine and cosine of $x$
and $y$, we can find the value of $cos(x - y)$ by using
the Subtraction Formula for Cosine. State the formula:
$cos(x - y)= cos\ x\ cos\ y + sin\ x\ sin\ y$
