$\"\"$

\

Need to prove $\"\"$ .

\

$\"\"$

\

Let $\"\"$

\

$\"\"$ .

\

$\"\"$

\

$\"\"$

\

Apply reciprocal identity: $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

Substitute $\"\"$ .

\

$\"\"$ .

\

$\"\"$

\

$\"\"$ .