$\"\"$

\

(a)

\

The expression is $\"\"$ .

\

Apply formula: $\"\"$ )

\

$\"\"$

\

$\"\"$

\

Substitute the values : $\"\"$ .

\

$\"\"$

\

$\"\"$ (Simplify)

\

$\"\"$ (Simplify)

\

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

\

$\"\"$

\

(b)

\

The expression is $\"\"$ .

\

Substitute the values : $\"\"$ .

\

$\"\"$

\

$\"\"$ (Simplify)

\

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

\

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

\

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