how to find the limits for this type of integrals using spherical coordinates












0












$begingroup$



move the integral



$int_0^1 int_0^{sqrt{1 - x^2}} int_0^{sqrt{1 - x^2 - y^2}} sqrt{x^2 + y^2 + z^2},mathrm dz,mathrm dy,mathrm dx = frac{pi}{8}$



to spherical coordinates integral.




i dont know how to find the limits of the integral when moving to $theta, r , phi $



can you please guide me with finding the limits because i always get a mistakes there




my trial :




reading the $mathrm dz$ we see that $ 0 leq z^2 leq 1-x^2-y^2 $
or $ 0leq x^2 + y^2 + z^2 leq 1 $



reading $mathrm dy$ we see that $ 0 leq y^2 leq sqrt{1-x^2} $ or $ 0leq x^2 + y^2 leq 1$



reading $dx$ we see that $ 0 leq x leq 1$



so the spherical limits :



$ 0leq r^2 leq 1$



$ 0 leq r^2sin(theta)^2 leq 1$



$ 0 leq rcos(theta)sin(phi) leq 1$




how do i continue from here ? i think i made a mistake with $phi$ because i didn't get the proper value for the integral after calculating in the spherical co-ordinates.











share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    You lost the point that $x,y,z$ are all positive
    $endgroup$
    – Damien
    Dec 25 '18 at 11:20
















0












$begingroup$



move the integral



$int_0^1 int_0^{sqrt{1 - x^2}} int_0^{sqrt{1 - x^2 - y^2}} sqrt{x^2 + y^2 + z^2},mathrm dz,mathrm dy,mathrm dx = frac{pi}{8}$



to spherical coordinates integral.




i dont know how to find the limits of the integral when moving to $theta, r , phi $



can you please guide me with finding the limits because i always get a mistakes there




my trial :




reading the $mathrm dz$ we see that $ 0 leq z^2 leq 1-x^2-y^2 $
or $ 0leq x^2 + y^2 + z^2 leq 1 $



reading $mathrm dy$ we see that $ 0 leq y^2 leq sqrt{1-x^2} $ or $ 0leq x^2 + y^2 leq 1$



reading $dx$ we see that $ 0 leq x leq 1$



so the spherical limits :



$ 0leq r^2 leq 1$



$ 0 leq r^2sin(theta)^2 leq 1$



$ 0 leq rcos(theta)sin(phi) leq 1$




how do i continue from here ? i think i made a mistake with $phi$ because i didn't get the proper value for the integral after calculating in the spherical co-ordinates.











share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    You lost the point that $x,y,z$ are all positive
    $endgroup$
    – Damien
    Dec 25 '18 at 11:20














0












0








0





$begingroup$



move the integral



$int_0^1 int_0^{sqrt{1 - x^2}} int_0^{sqrt{1 - x^2 - y^2}} sqrt{x^2 + y^2 + z^2},mathrm dz,mathrm dy,mathrm dx = frac{pi}{8}$



to spherical coordinates integral.




i dont know how to find the limits of the integral when moving to $theta, r , phi $



can you please guide me with finding the limits because i always get a mistakes there




my trial :




reading the $mathrm dz$ we see that $ 0 leq z^2 leq 1-x^2-y^2 $
or $ 0leq x^2 + y^2 + z^2 leq 1 $



reading $mathrm dy$ we see that $ 0 leq y^2 leq sqrt{1-x^2} $ or $ 0leq x^2 + y^2 leq 1$



reading $dx$ we see that $ 0 leq x leq 1$



so the spherical limits :



$ 0leq r^2 leq 1$



$ 0 leq r^2sin(theta)^2 leq 1$



$ 0 leq rcos(theta)sin(phi) leq 1$




how do i continue from here ? i think i made a mistake with $phi$ because i didn't get the proper value for the integral after calculating in the spherical co-ordinates.











share|cite|improve this question











$endgroup$





move the integral



$int_0^1 int_0^{sqrt{1 - x^2}} int_0^{sqrt{1 - x^2 - y^2}} sqrt{x^2 + y^2 + z^2},mathrm dz,mathrm dy,mathrm dx = frac{pi}{8}$



to spherical coordinates integral.




i dont know how to find the limits of the integral when moving to $theta, r , phi $



can you please guide me with finding the limits because i always get a mistakes there




my trial :




reading the $mathrm dz$ we see that $ 0 leq z^2 leq 1-x^2-y^2 $
or $ 0leq x^2 + y^2 + z^2 leq 1 $



reading $mathrm dy$ we see that $ 0 leq y^2 leq sqrt{1-x^2} $ or $ 0leq x^2 + y^2 leq 1$



reading $dx$ we see that $ 0 leq x leq 1$



so the spherical limits :



$ 0leq r^2 leq 1$



$ 0 leq r^2sin(theta)^2 leq 1$



$ 0 leq rcos(theta)sin(phi) leq 1$




how do i continue from here ? i think i made a mistake with $phi$ because i didn't get the proper value for the integral after calculating in the spherical co-ordinates.








integration multivariable-calculus spherical-coordinates jacobian






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 25 '18 at 11:44









José Carlos Santos

173k23133241




173k23133241










asked Dec 25 '18 at 10:51









Mather Mather

4028




4028








  • 1




    $begingroup$
    You lost the point that $x,y,z$ are all positive
    $endgroup$
    – Damien
    Dec 25 '18 at 11:20














  • 1




    $begingroup$
    You lost the point that $x,y,z$ are all positive
    $endgroup$
    – Damien
    Dec 25 '18 at 11:20








1




1




$begingroup$
You lost the point that $x,y,z$ are all positive
$endgroup$
– Damien
Dec 25 '18 at 11:20




$begingroup$
You lost the point that $x,y,z$ are all positive
$endgroup$
– Damien
Dec 25 '18 at 11:20










1 Answer
1






active

oldest

votes


















0












$begingroup$

It follows from your computations that your integral is equal to$$int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr.$$Butbegin{align}int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr&=left(int_0^1r^3,mathrm drright)left(int_0^{fracpi2}sin(phi),mathrm dphiright)left(int_0^{fracpi2},mathrm dthetaright)\&=frac14times1timesfracpi2\&=fracpi8.end{align}






share|cite|improve this answer









$endgroup$













  • $begingroup$
    how did you know that $ 0 leq theta leq frac{pi}{2} $
    $endgroup$
    – Mather
    Dec 25 '18 at 11:36












  • $begingroup$
    Because $x,y,zleqslant0$.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:38










  • $begingroup$
    also why is $ 0leq r leq 1 $ and not $ 0leq r leq frac{1}{sin{theta} }$
    $endgroup$
    – Mather
    Dec 25 '18 at 11:38












  • $begingroup$
    Why should we have that? The region that you are interested in is the part of the unit sphere in which all Cartesian coordinates are non-negative. So, $r$ can take any value from $0$ to $1$, whatever $theta$ may be.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:42












  • $begingroup$
    yes but the inequality says (by moving from xyz , to spherical ) that $ 0 leq r^2sin(theta)^2 leq 1 $ so dividing makes the ineuality $(a)$ $ 0leq r leq frac{1}{sin(theta)} $ doesn't it ?
    $endgroup$
    – Mather
    Dec 25 '18 at 11:46














Your Answer





StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3052005%2fhow-to-find-the-limits-for-this-type-of-integrals-using-spherical-coordinates%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









0












$begingroup$

It follows from your computations that your integral is equal to$$int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr.$$Butbegin{align}int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr&=left(int_0^1r^3,mathrm drright)left(int_0^{fracpi2}sin(phi),mathrm dphiright)left(int_0^{fracpi2},mathrm dthetaright)\&=frac14times1timesfracpi2\&=fracpi8.end{align}






share|cite|improve this answer









$endgroup$













  • $begingroup$
    how did you know that $ 0 leq theta leq frac{pi}{2} $
    $endgroup$
    – Mather
    Dec 25 '18 at 11:36












  • $begingroup$
    Because $x,y,zleqslant0$.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:38










  • $begingroup$
    also why is $ 0leq r leq 1 $ and not $ 0leq r leq frac{1}{sin{theta} }$
    $endgroup$
    – Mather
    Dec 25 '18 at 11:38












  • $begingroup$
    Why should we have that? The region that you are interested in is the part of the unit sphere in which all Cartesian coordinates are non-negative. So, $r$ can take any value from $0$ to $1$, whatever $theta$ may be.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:42












  • $begingroup$
    yes but the inequality says (by moving from xyz , to spherical ) that $ 0 leq r^2sin(theta)^2 leq 1 $ so dividing makes the ineuality $(a)$ $ 0leq r leq frac{1}{sin(theta)} $ doesn't it ?
    $endgroup$
    – Mather
    Dec 25 '18 at 11:46


















0












$begingroup$

It follows from your computations that your integral is equal to$$int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr.$$Butbegin{align}int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr&=left(int_0^1r^3,mathrm drright)left(int_0^{fracpi2}sin(phi),mathrm dphiright)left(int_0^{fracpi2},mathrm dthetaright)\&=frac14times1timesfracpi2\&=fracpi8.end{align}






share|cite|improve this answer









$endgroup$













  • $begingroup$
    how did you know that $ 0 leq theta leq frac{pi}{2} $
    $endgroup$
    – Mather
    Dec 25 '18 at 11:36












  • $begingroup$
    Because $x,y,zleqslant0$.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:38










  • $begingroup$
    also why is $ 0leq r leq 1 $ and not $ 0leq r leq frac{1}{sin{theta} }$
    $endgroup$
    – Mather
    Dec 25 '18 at 11:38












  • $begingroup$
    Why should we have that? The region that you are interested in is the part of the unit sphere in which all Cartesian coordinates are non-negative. So, $r$ can take any value from $0$ to $1$, whatever $theta$ may be.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:42












  • $begingroup$
    yes but the inequality says (by moving from xyz , to spherical ) that $ 0 leq r^2sin(theta)^2 leq 1 $ so dividing makes the ineuality $(a)$ $ 0leq r leq frac{1}{sin(theta)} $ doesn't it ?
    $endgroup$
    – Mather
    Dec 25 '18 at 11:46
















0












0








0





$begingroup$

It follows from your computations that your integral is equal to$$int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr.$$Butbegin{align}int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr&=left(int_0^1r^3,mathrm drright)left(int_0^{fracpi2}sin(phi),mathrm dphiright)left(int_0^{fracpi2},mathrm dthetaright)\&=frac14times1timesfracpi2\&=fracpi8.end{align}






share|cite|improve this answer









$endgroup$



It follows from your computations that your integral is equal to$$int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr.$$Butbegin{align}int_0^1int_0^{fracpi2}int_0^{fracpi2}r^3sin(phi),mathrm dtheta,mathrm dphi,mathrm dr&=left(int_0^1r^3,mathrm drright)left(int_0^{fracpi2}sin(phi),mathrm dphiright)left(int_0^{fracpi2},mathrm dthetaright)\&=frac14times1timesfracpi2\&=fracpi8.end{align}







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 25 '18 at 11:34









José Carlos SantosJosé Carlos Santos

173k23133241




173k23133241












  • $begingroup$
    how did you know that $ 0 leq theta leq frac{pi}{2} $
    $endgroup$
    – Mather
    Dec 25 '18 at 11:36












  • $begingroup$
    Because $x,y,zleqslant0$.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:38










  • $begingroup$
    also why is $ 0leq r leq 1 $ and not $ 0leq r leq frac{1}{sin{theta} }$
    $endgroup$
    – Mather
    Dec 25 '18 at 11:38












  • $begingroup$
    Why should we have that? The region that you are interested in is the part of the unit sphere in which all Cartesian coordinates are non-negative. So, $r$ can take any value from $0$ to $1$, whatever $theta$ may be.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:42












  • $begingroup$
    yes but the inequality says (by moving from xyz , to spherical ) that $ 0 leq r^2sin(theta)^2 leq 1 $ so dividing makes the ineuality $(a)$ $ 0leq r leq frac{1}{sin(theta)} $ doesn't it ?
    $endgroup$
    – Mather
    Dec 25 '18 at 11:46




















  • $begingroup$
    how did you know that $ 0 leq theta leq frac{pi}{2} $
    $endgroup$
    – Mather
    Dec 25 '18 at 11:36












  • $begingroup$
    Because $x,y,zleqslant0$.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:38










  • $begingroup$
    also why is $ 0leq r leq 1 $ and not $ 0leq r leq frac{1}{sin{theta} }$
    $endgroup$
    – Mather
    Dec 25 '18 at 11:38












  • $begingroup$
    Why should we have that? The region that you are interested in is the part of the unit sphere in which all Cartesian coordinates are non-negative. So, $r$ can take any value from $0$ to $1$, whatever $theta$ may be.
    $endgroup$
    – José Carlos Santos
    Dec 25 '18 at 11:42












  • $begingroup$
    yes but the inequality says (by moving from xyz , to spherical ) that $ 0 leq r^2sin(theta)^2 leq 1 $ so dividing makes the ineuality $(a)$ $ 0leq r leq frac{1}{sin(theta)} $ doesn't it ?
    $endgroup$
    – Mather
    Dec 25 '18 at 11:46


















$begingroup$
how did you know that $ 0 leq theta leq frac{pi}{2} $
$endgroup$
– Mather
Dec 25 '18 at 11:36






$begingroup$
how did you know that $ 0 leq theta leq frac{pi}{2} $
$endgroup$
– Mather
Dec 25 '18 at 11:36














$begingroup$
Because $x,y,zleqslant0$.
$endgroup$
– José Carlos Santos
Dec 25 '18 at 11:38




$begingroup$
Because $x,y,zleqslant0$.
$endgroup$
– José Carlos Santos
Dec 25 '18 at 11:38












$begingroup$
also why is $ 0leq r leq 1 $ and not $ 0leq r leq frac{1}{sin{theta} }$
$endgroup$
– Mather
Dec 25 '18 at 11:38






$begingroup$
also why is $ 0leq r leq 1 $ and not $ 0leq r leq frac{1}{sin{theta} }$
$endgroup$
– Mather
Dec 25 '18 at 11:38














$begingroup$
Why should we have that? The region that you are interested in is the part of the unit sphere in which all Cartesian coordinates are non-negative. So, $r$ can take any value from $0$ to $1$, whatever $theta$ may be.
$endgroup$
– José Carlos Santos
Dec 25 '18 at 11:42






$begingroup$
Why should we have that? The region that you are interested in is the part of the unit sphere in which all Cartesian coordinates are non-negative. So, $r$ can take any value from $0$ to $1$, whatever $theta$ may be.
$endgroup$
– José Carlos Santos
Dec 25 '18 at 11:42














$begingroup$
yes but the inequality says (by moving from xyz , to spherical ) that $ 0 leq r^2sin(theta)^2 leq 1 $ so dividing makes the ineuality $(a)$ $ 0leq r leq frac{1}{sin(theta)} $ doesn't it ?
$endgroup$
– Mather
Dec 25 '18 at 11:46






$begingroup$
yes but the inequality says (by moving from xyz , to spherical ) that $ 0 leq r^2sin(theta)^2 leq 1 $ so dividing makes the ineuality $(a)$ $ 0leq r leq frac{1}{sin(theta)} $ doesn't it ?
$endgroup$
– Mather
Dec 25 '18 at 11:46




















draft saved

draft discarded




















































Thanks for contributing an answer to Mathematics Stack Exchange!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


Use MathJax to format equations. MathJax reference.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3052005%2fhow-to-find-the-limits-for-this-type-of-integrals-using-spherical-coordinates%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

Bundesstraße 106

Le Mesnil-Réaume

Ida-Boy-Ed-Garten