Area for slicing


by icystrike
Tags: slicing
icystrike
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#1
Mar15-11, 12:58 AM
P: 439
Can i ask what is the area we are refering to when we take such integral (r is the radius):

[tex]\int_{-\infty }^{\infty }e^{-r^{2}}dr[/tex]

I'm suspecting that its is the area of slices of bell curve that rotates about the z-axis.

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tiny-tim
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#2
Mar15-11, 06:07 AM
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hi icystrike!

it's the integral of a vertical slice of the bell curve through its centre
HallsofIvy
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#3
Mar15-11, 06:11 AM
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You understand, I hope, that finding area is one possible application of the integral. When we calculate an integral we are not necessarily finding any area at all!

icystrike
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#4
Mar15-11, 01:42 PM
P: 439

Area for slicing


Thanks tiny-tim and HallsofIvy!

Yes! I know that! We can use Integral to compute things like work, flux, centroids .. =D

Its just that my teacher actually relate the slice as "some slice that is parallel to the y-axis" while i think that it should be the slice that is passing through origin(He've probably made some mistake)... (My teacher was actually comparing the volume of a rotated bell curve about z axis by slice and shells to evaluate the area under bell curve - [tex]A^{2}=\pi[/tex] )
tiny-tim
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Mar15-11, 01:47 PM
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hi icystrike!
Quote Quote by icystrike View Post
Its just that my teacher actually relate the slice as "some slice that is parallel to the y-axis" while i think that it should be the slice that is passing through origin
i think he means that it'll be the same (it's the same shape), apart from a factor e-x2
icystrike
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#6
Mar15-11, 02:14 PM
P: 439
Oh! Thats what he meant! Truly enlighten! Thanks Tim! :)
(Came to ensure that i get the concept right)


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