Step 1:

(a)

The identity is $\"\"$ for $\"\"$ .

Consider $\"\"$

Definition of inverse trigonometry function: $\"\"$ then $\"\"$

$\"\"$

Substitute $\"\"$ .

$\"\"$

Step 2:

(b)

The function is $\"\"$ for $\"\"$ .

Consider $\"\"$

Take tangent of each side.

$\"\"$

Sum formula of tangent function: $\"\"$ .

$\"\"$

Properties of inverse trigonometry function $\"\"$

$\"\"$

$\"\"$ .

Solution:

(a) $\"\"$ .

(b) $\"\"$ .