$\"\"$

\

The function is $\"\"$ .

\

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

\

$\"\"$ .

\

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

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Pythagorean identity: $\"\"$ .

\

$\"\"$

\

Slope of the tangent is derivative of the function.

\

$\"\"$ .

\

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

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

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

\

$\"\"$ .

\

$\"\"$

\

$\"\"$ .