$\"\"$

(a)

The expression is $\"\"$ .

Use the properties of inverse trigonometric function: $\"\"$

$\"\"$

The exact value of expression $\"\"$

$\"\"$

(b)

The expression is $\"\"$ .

Rewrite the above expression $\"\"$

From trigonimetric identities $\"\"$

$\"\"$

Use the properties of inverse trigonometric function: $\"\"$ .

$\"\"$

The exact value of expression $\"\"$ .

$\"\"$

(a)

The exact value of expression $\"\"$

(b)

The exact value of expression $\"\"$ .