$\"\"$

The identity is $\"\"$ .

To take the right hand side expression for prove that left hand side expression.

$\"\"$

(Apply quotient identities: $\"\"$ )

$\"\"$

(Add denominator: $\"\"$ )

$\"\"$ $\"\"$

$\"\"$ (Divide: $\"\"$ )

$\"\"$ (Apply Pythagorean identity: $\"\"$ )

$\"\"$ (Apply reciprocal identity: $\"\"$ ) $\"\"$

$\"\"$ is an identity.