- #1
yesiammanu
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Homework Statement
Find the volume of the solid generated by revolving the region bounded by the graphs of y2=4x, the line y=x, about
A) x=4
B) y=4
So first I start out by graphing it
The intercepts are at 0,0 and 4,4
I use the washers method since there is a gap in between the line and the rotated solid, making a space in the middle of the solid
The washers method says V= ∏∫ ([R(x)]2 - [r(x)2) where R(x) is the largest(outer) area, and r(x) is the smallest(inside) area. This is for rotating about the x-axis but can be used to rotate around the y axis. However, this isn't rotating about either of these axis; rather, it's rotating around x=4 which is what I am having trouble with.
So boundaries are 0 to 4, equation is ∏∫([y2/4]2 - y2)dy but this is wrong. How would I do it correctly? Is cylindrical shells a better method? If I was using cylindrical shells, would it be 2∏∫(2√x - x)(x) since I use ∫ 2∏(shell height)(shell radius) Also I'm a bit confused on how I would do part B
Any help would be great, thanks.
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