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Lo.Lee.Ta.

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So this is the one I'm working on:

1. "Find the volume of the solid described below:

The solid lies between the planes perpendicular to the x-axis at x=6 and x=-6. The cross-sections perpendicular to the axis on the interval -6≤x≤6 are squares whose bases run from the semicircle y= -√(36 - x^2) to the semicircle y= √(36 - x^2)."2. I first drew out the object, which is a sphere with a radius of 6.

Every cross-section is a square, so each will have an area s^2. The area of each cross-section is 2(√(36 - x^2))^2.

To find the volume, the dx represents the thickness of each square that fills the sphere.

2∫-6 to 6 of (√(36 - x^2))^2

= 2∫36 - x^2

= 2(36x - (x^3)/3)dx |-6 to 6

= Plug in values... Answer = 576units^3

But this is counted as the wrong answer! What am I doing wrong here?! :/

Thanks for your help! :)