CPM Homework Help : APCALC Problem 3-67

Expand each of the following trig expressions.

$\sin(x+y)$

$\cos(x+y)$

$\sin(x−y)$

$\cos(x−y)$

Hint:

Angle Sum
$\sin\left(a\pm b\right)=\sin\left(a\right)\cos\left(b\right)\pm\cos\left(a\right)\sin\left(b\right)$
$\cos\left(a\pm b\right)=\cos\left(a\right)\cos\left(b\right)∓\sin\left(a\right)\sin\left(b\right)$