Find the area of the surface obtained by rotating the circle x^2 + y^2 = a^2 about the line y=a. The y=a confuses me. What's the answer?
Last edited by jamessmith; October 10th 2009 at 05:38 PM.
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Originally Posted by jamessmith The y=a confuses me. What's the answer? Did ya at least give it a shot? Nothing has changed here. Note that this is a circle with radius a (So... wherre will y=a be?). Also, when you differentiate, treat a like the constant that it is. You can do this.
Originally Posted by jamessmith Find the area of the surface obtained by rotating the circle x^2 + y^2 = a^2 about the line y=a. The y=a confuses me. What's the answer? Translate everything down by units. Therefore rotate around the x-axis (I assume you know the formula for doing this).
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