$\"\"$

(a)

The curve is $\"\"$ where $\"\"$ .

$\"\"$

The differential of arc length : $\"\"$ .

Consider $\"\"$ .

Differentiate with respect to $\"\"$ .

$\"\"$

Substitute $\"\"$ in $\"\"$ .

$\"\"$

Surface area of the curve when rotated about $\"\"$ -axis : $\"\"$ .

Substitute $\"\"$ and $\"\"$ in the above formula.

$\"\"$

The surface area is $\"\"$ .