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 03-29-2010, 06:49 PM #1 Junior Member   Join Date: Jan 2009 Posts: 138 help with AP calc question, thanks find the area of the region inside r=10sin(theta) but outside r=3 i get 154.08 as an answer but that doesnt seem to be correct Reply
 03-29-2010, 06:58 PM #2 Senior Member   Join Date: Feb 2010 Location: UChicago '15 Posts: 1,642 Is r=3 a vertical line or a horizontal line? Reply
 03-29-2010, 07:04 PM #3 Senior Member   Join Date: Feb 2010 Location: UChicago '15 Posts: 1,642 I'm getting 11.48 as the answer, assuming that r=3 is a horizontal line. Graph the two functions on your calculator: y=10sin(x) and y=3. You'll notice that they are asking for the area between these two curves. I'll be taking vertical strips, so the limits of integration are decided by the x coordinates of the intersection of the two curves. The two x coordinates are: .30469265 and 2.8369. I now integrate (10sin(x) - 3) from .30469265 to 2.8369 and get 11.48. Sound good? Reply
 03-29-2010, 07:19 PM #4 Junior Member   Join Date: Jan 2009 Posts: 138 hmm these are polar equations, isnt the formula for area of a polar equation integral (.5r^2)? Reply
 03-29-2010, 07:22 PM #5 Junior Member   Join Date: Jan 2009 Posts: 138 i found the answer, its 66.193 integral of 0.5 ((10 sin(x))^2-3^2) from x=.304 to 2.8369 dx = 66.2193 Reply
 03-29-2010, 07:24 PM #6 Senior Member   Join Date: Feb 2010 Location: UChicago '15 Posts: 1,642 I'm a moron lol. My bad. Reply

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