
#1
Mar1511, 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 zaxis. 



#2
Mar1511, 06:07 AM

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P: 26,167

hi icystrike!
it's the integral of a vertical slice of the bell curve through its centre 



#3
Mar1511, 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!




#4
Mar1511, 01:42 PM

P: 439

Area for slicing
Thanks tinytim 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 yaxis" 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] ) 



#5
Mar1511, 01:47 PM

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hi icystrike!




#6
Mar1511, 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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