The function is $\"\"$ .

Rewrite the expression.

$\"\"$

Differentiate on each side with respect to $\"\"$ .

$\"\"$

Sum rule of derivatives: $\"\"$ .

$\"\"$

Constant multiple rule of derivatives: $\"\"$ .

$\"\"$

Power rule of derivatives: $\"\"$

Derivative of a cosine function: $\"\"$ .

$\"\"$

$\"\"$ .

$\"\"$

$\"\"$ .