Calculating Surface Area of Rotated Functions

[vinsento]

Homework Statement

Find the surface area of the solid obtained by rotating
y = √9 − X^2 , − 2 ≤ X ≤ 2 about the X-axis.

Homework Equations

∏r^2

The Attempt at a Solution

Y = (9 - x^2)^-1/2
Is that can do like this..
then how bout the power inside the X^2??

 

[mfb]

∏r^2

That formula applies to circles only.

There is a general formula for surface areas of rotated functions. It is possible to derive it, but usually this is not expected for those tasks, so I think the formula is given somewhere.

Alternatively, draw a sketch of the function. Rotated around the x-axis, it is a well-known object where the surface is easy to calculate.