$\"\"$

\

The trigonometric expression is $\"\"$

\

Use double - angle formula: $\"\"$ .

\

$\"\"$

\

Simplify $\"\"$ .

\

Use inverse trigonometric functions: $\"\"$ .

\

$\"\"$ .

\

$\"\"$

\

Simplify $\"\"$ .

\

Let $\"\"$ , then $\"\"$ .

\

$\"\"$ .

\

From Pythagorean theorem,

\

$\"\"$

\

$\"\"$

\

$\"\"$ .

\

Substitute $\"\"$ in $\"\"$ .

\

$\"\"$ . \ \

\

Substitute $\"\"$ and $\"\"$ in equation (1).

\

$\"\"$

\

$\"\"$

\

$\"\"$ .