$\"\"$

\

The trigonometric identity is $\"\"$ .

\

Consider left hand side identity : $\"\"$ .

\

Apply product rule of logarithm : $\"\"$ .

\

$\"\"$

\

Pythagorean identity : $\"\"$ .

\

$\"\"$

\

Apply power rule of logarithm : $\"\"$ .

\

$\"\"$

\

= Right hand side identity.

\

$\"\"$

\

$\"\"$ .