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Mathematics 7 Online
OpenStudy (anonymous):

volume of solid bounded by cone x^2+y^2=z^2 and paraboloid x^2 +y^2=z above xy plane....ty picture attached at second post....ty

OpenStudy (anonymous):

OpenStudy (anonymous):

I did first to try to find intersection of both cone and paraboloid is it?

OpenStudy (anonymous):

@ash2326 this is the final question for now i need your help hope you dun mind? ty so much for the other 4....

OpenStudy (ash2326):

angalc557 I'm so sorry but I don't know this one. Ask for help in chat.

OpenStudy (nikvist):

\[z^2=x^2+y^2\quad,\quad z=x^2+y^2\]\[z^2=z\quad\Rightarrow\quad z=0\quad\vee\quad z=1\]\[S:\quad x^2+y^2=1\]\[V=\iint\limits_S\left(\sqrt{x^2+y^2}-(x^2+y^2)\right)dxdy\]\[x=\rho\cos\phi\quad,\quad y=\rho\sin\phi\quad,\quad dxdy=\rho d\rho d\phi\]\[V=\iint\limits_S\left(\rho-\rho^2\right)\rho d\rho d\phi=\int\limits_0^{2\pi} d\phi\int\limits_0^1 \left(\rho^2-\rho^3\right)d\rho=\]\[=2\pi\left(\frac{\rho^3}{3}-\frac{\rho^4}{4}\right)|_0^1=2\pi\left(\frac{1}{3}-\frac{1}{4}\right)=\frac{\pi}{6}\]

OpenStudy (anonymous):

@nikvist nicely guided hmm i would like to ask the cone is facing downwards and the paraboloid is facing upwards in terms of 3d maybe you could just sketch it out the image for me to clearly understand....ty ;)

OpenStudy (nikvist):

2D space

OpenStudy (anonymous):

so if written in words means the region of integration is bounded from above or below the paraboloid and from below or above the cone.....hard to imagine haha....? ty

OpenStudy (nikvist):

cone-above , paraboloid-below

OpenStudy (anonymous):

hmm @nikvist actually i was thinking few days i thought the volume of D is between the outer parabola and the inner conic can u refer my drawing to confirm....haha|dw:1330344099879:dw| right? or my drawing is wrong...??

OpenStudy (nikvist):

picture is OK

OpenStudy (anonymous):

means in that case the region bounded is the paraboloid minus the cone but ur equation is cone minus paraboloid right?

OpenStudy (nikvist):

cone-paraboloid

OpenStudy (anonymous):

means the region is between both lines or inside the conic area?

OpenStudy (anonymous):

so i thought is the outer minus the inner volume so means paraboloid minus cone could u enlighten me why u think is cone minus paraboloid based on the diagram...?? i so confused....ty so much :)

OpenStudy (nikvist):

between both lines

OpenStudy (anonymous):

i see that what i was imagining so means i thought the volume normally will be the outer minus the inner right? somewhere i am wrong?

OpenStudy (nikvist):

your method is OK, but you can't find volume of parabolid without integration.

OpenStudy (anonymous):

let me just ask for my extra knowledge @nikvist why cant be volume of paraboloid minus the cone in the volume equation u stated....?? thanks

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