$\"\"$

The trigonometric expression is $\"\"$ .

Rewrite the expression as $\"\"$ .

Consider $\"\"$ , then $\"\"$ .

Definition of inverse trigonometric function : $\"\"$ .

If $\"\"$ , then $\"\"$ .

The relationship between $\"\"$ and $\"\"$ can be represented by a right triangle.

$\"\"$

Observe the figure,

Here $\"\"$ and $\"\"$ .

$\"\"$ .

$\"\"$ . $\"\"$

$\"\"$ .