Region is bounded by the graphs , ,  and .

Find the surface area of the solid generated by revolving the region about axis.

Definition of the surface area :

If the curve , , then the surface area of the curve is defined as

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Consider .

Differentiate on each side with respect to .

.

And here .

Substitute corresponding values in the formula.

Find the integral using trigonometric substitution.

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Formula : .

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If  then .

Consider .

.

Surface area of the solid is  sq-units.

Surface area of the solid is  sq-units.