Determine the surface area

  • Thread starter vinsento
  • Start date
  • #1
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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??

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
35,437
11,857
∏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.
 

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