$\"\"$

The function is $\"\"$ .

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

$\"\"$

Derivative of the sine function: $\"\"$ .

$\"\"$ .

Slope of the tangent is derivative of the function.

$\"\"$ .

The function has horizontal tangent where slope of the tangent is zero.

Thus, $\"\"$

$\"\"$ .

General solution of $\"\"$ is $\"\"$ .

$\"\"$

$\"\"$ .