$\"\"$

Prove $\"\"$

Consider the function $\"\"$ .

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

$\"\"$

Trigonometric quotient identity: $\"\"$ .

$\"\"$

Quotient of derivatives: $\"\"$ .

$\"\"$

Trigonometric identity: $\"\"$ .

$\"\"$

Trigonometric reciprocal identity: $\"\"$ .

$\"\"$ .

$\"\"$