$\"\"$

(a)

The expression is $\"\"$ .

Apply formula : $\"\"$

$\"\"$

Substitute the values : $\"\"$

$\"\"$

$\"\"$ \ \

$\"\"$ .

$\"\"$

(b)

The expression is $\"\"$ .

Substitute the values : $\"\"$

$\"\"$

$\"\"$ ( $\"\"$ ) $\"\"$

(a) The exact value of the expression $\"\"$ is $\"\"$ .

(b) The exact value of the expression $\"\"$ is 1.2071.