finding integral of $ sqrt {50-50cos(t)} $












0












$begingroup$


I have a cycloide



$ {x(t)=5 (t-sin(t)), y(t)=5(1-cos(t))} $ and



$ {x(t)=5 (t-sin(t)), y(t)=-5(1-cos(t))} $



and the aim is to find the circumference and to find it I have to show and take the differentiate integral:



$$ int sqrt{50-50cos(t)} dt $$



so I need help with it



Is the right anwser $ frac{-20}{sqrt{tan^2( frac{t}{2})+1}} $ ??










share|cite|improve this question











$endgroup$












  • $begingroup$
    You should really add that $mathrm dt$ at the end.
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 5 '18 at 0:47






  • 1




    $begingroup$
    Factor out $sqrt{50}$ and use my least favorite change of variables: $tan(t/2) = u.$
    $endgroup$
    – Sean Roberson
    Dec 5 '18 at 0:49
















0












$begingroup$


I have a cycloide



$ {x(t)=5 (t-sin(t)), y(t)=5(1-cos(t))} $ and



$ {x(t)=5 (t-sin(t)), y(t)=-5(1-cos(t))} $



and the aim is to find the circumference and to find it I have to show and take the differentiate integral:



$$ int sqrt{50-50cos(t)} dt $$



so I need help with it



Is the right anwser $ frac{-20}{sqrt{tan^2( frac{t}{2})+1}} $ ??










share|cite|improve this question











$endgroup$












  • $begingroup$
    You should really add that $mathrm dt$ at the end.
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 5 '18 at 0:47






  • 1




    $begingroup$
    Factor out $sqrt{50}$ and use my least favorite change of variables: $tan(t/2) = u.$
    $endgroup$
    – Sean Roberson
    Dec 5 '18 at 0:49














0












0








0





$begingroup$


I have a cycloide



$ {x(t)=5 (t-sin(t)), y(t)=5(1-cos(t))} $ and



$ {x(t)=5 (t-sin(t)), y(t)=-5(1-cos(t))} $



and the aim is to find the circumference and to find it I have to show and take the differentiate integral:



$$ int sqrt{50-50cos(t)} dt $$



so I need help with it



Is the right anwser $ frac{-20}{sqrt{tan^2( frac{t}{2})+1}} $ ??










share|cite|improve this question











$endgroup$




I have a cycloide



$ {x(t)=5 (t-sin(t)), y(t)=5(1-cos(t))} $ and



$ {x(t)=5 (t-sin(t)), y(t)=-5(1-cos(t))} $



and the aim is to find the circumference and to find it I have to show and take the differentiate integral:



$$ int sqrt{50-50cos(t)} dt $$



so I need help with it



Is the right anwser $ frac{-20}{sqrt{tan^2( frac{t}{2})+1}} $ ??







integration indefinite-integrals






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 5 '18 at 1:13







Student123

















asked Dec 5 '18 at 0:44









Student123Student123

536




536












  • $begingroup$
    You should really add that $mathrm dt$ at the end.
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 5 '18 at 0:47






  • 1




    $begingroup$
    Factor out $sqrt{50}$ and use my least favorite change of variables: $tan(t/2) = u.$
    $endgroup$
    – Sean Roberson
    Dec 5 '18 at 0:49


















  • $begingroup$
    You should really add that $mathrm dt$ at the end.
    $endgroup$
    – Mohammad Zuhair Khan
    Dec 5 '18 at 0:47






  • 1




    $begingroup$
    Factor out $sqrt{50}$ and use my least favorite change of variables: $tan(t/2) = u.$
    $endgroup$
    – Sean Roberson
    Dec 5 '18 at 0:49
















$begingroup$
You should really add that $mathrm dt$ at the end.
$endgroup$
– Mohammad Zuhair Khan
Dec 5 '18 at 0:47




$begingroup$
You should really add that $mathrm dt$ at the end.
$endgroup$
– Mohammad Zuhair Khan
Dec 5 '18 at 0:47




1




1




$begingroup$
Factor out $sqrt{50}$ and use my least favorite change of variables: $tan(t/2) = u.$
$endgroup$
– Sean Roberson
Dec 5 '18 at 0:49




$begingroup$
Factor out $sqrt{50}$ and use my least favorite change of variables: $tan(t/2) = u.$
$endgroup$
– Sean Roberson
Dec 5 '18 at 0:49










2 Answers
2






active

oldest

votes


















0












$begingroup$

$$sqrt{50-50cos x}=sqrt{50}sqrt{1 - cos x} =sqrt{50}sqrt{2 sin^2 frac{x} {2}}=10left| sinfrac{x} {2}right| $$
Can you finish now using this?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14






  • 2




    $begingroup$
    Yes, your answer is correct. You can also simplify it to:$$frac{-20}{sqrt{tan^2 frac{t}{2}+1}} =frac{-20}{sqrt{sec^2 frac{t}{2}}} =-20left|cos frac{x} {2} right|$$ And of course you need to add $+C$. And if you differentiate it you should see that we find what I left in the answer.
    $endgroup$
    – Zacky
    Dec 5 '18 at 1:20












  • $begingroup$
    how did you simplify that?
    $endgroup$
    – Student123
    Dec 5 '18 at 8:27










  • $begingroup$
    Oh, I just realised that I used $x$ in the last part instead of $t$. To prove it I will denote $frac{t}{2}=z$ then we have: $$frac{1}{sqrt{tan^2 z+1}} =frac{1}{sqrt{frac{sin^2 z}{cos^2 z}+1}}=frac{1}{sqrt{frac{sin^2z+cos^2 z}{cos^2 z}}}=frac{1}{sqrt{frac{1}{cos^2 z}}} =sqrt{cos^2 z} =left|cos zright|$$ $$Rightarrow frac{-20}{sqrt{tan^2 frac{t}{2}+1}}=-20left|cos frac{t}{2} right|$$
    $endgroup$
    – Zacky
    Dec 5 '18 at 9:52












  • $begingroup$
    Something is wrong, because when I replace t from $ 2pi $ to 0, the circumference comes 0
    $endgroup$
    – Student123
    Dec 6 '18 at 0:47





















0












$begingroup$

Hint:



$$sqrt{50-50cos(t)}=sqrt{50}cdot sqrt{1-cos(t)}$$



and



$$sqrt{1-cos(t)}=sqrt{2}cdot|sin(t/2)| $$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14











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%2f3026417%2ffinding-integral-of-sqrt-50-50-cost%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes









0












$begingroup$

$$sqrt{50-50cos x}=sqrt{50}sqrt{1 - cos x} =sqrt{50}sqrt{2 sin^2 frac{x} {2}}=10left| sinfrac{x} {2}right| $$
Can you finish now using this?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14






  • 2




    $begingroup$
    Yes, your answer is correct. You can also simplify it to:$$frac{-20}{sqrt{tan^2 frac{t}{2}+1}} =frac{-20}{sqrt{sec^2 frac{t}{2}}} =-20left|cos frac{x} {2} right|$$ And of course you need to add $+C$. And if you differentiate it you should see that we find what I left in the answer.
    $endgroup$
    – Zacky
    Dec 5 '18 at 1:20












  • $begingroup$
    how did you simplify that?
    $endgroup$
    – Student123
    Dec 5 '18 at 8:27










  • $begingroup$
    Oh, I just realised that I used $x$ in the last part instead of $t$. To prove it I will denote $frac{t}{2}=z$ then we have: $$frac{1}{sqrt{tan^2 z+1}} =frac{1}{sqrt{frac{sin^2 z}{cos^2 z}+1}}=frac{1}{sqrt{frac{sin^2z+cos^2 z}{cos^2 z}}}=frac{1}{sqrt{frac{1}{cos^2 z}}} =sqrt{cos^2 z} =left|cos zright|$$ $$Rightarrow frac{-20}{sqrt{tan^2 frac{t}{2}+1}}=-20left|cos frac{t}{2} right|$$
    $endgroup$
    – Zacky
    Dec 5 '18 at 9:52












  • $begingroup$
    Something is wrong, because when I replace t from $ 2pi $ to 0, the circumference comes 0
    $endgroup$
    – Student123
    Dec 6 '18 at 0:47


















0












$begingroup$

$$sqrt{50-50cos x}=sqrt{50}sqrt{1 - cos x} =sqrt{50}sqrt{2 sin^2 frac{x} {2}}=10left| sinfrac{x} {2}right| $$
Can you finish now using this?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14






  • 2




    $begingroup$
    Yes, your answer is correct. You can also simplify it to:$$frac{-20}{sqrt{tan^2 frac{t}{2}+1}} =frac{-20}{sqrt{sec^2 frac{t}{2}}} =-20left|cos frac{x} {2} right|$$ And of course you need to add $+C$. And if you differentiate it you should see that we find what I left in the answer.
    $endgroup$
    – Zacky
    Dec 5 '18 at 1:20












  • $begingroup$
    how did you simplify that?
    $endgroup$
    – Student123
    Dec 5 '18 at 8:27










  • $begingroup$
    Oh, I just realised that I used $x$ in the last part instead of $t$. To prove it I will denote $frac{t}{2}=z$ then we have: $$frac{1}{sqrt{tan^2 z+1}} =frac{1}{sqrt{frac{sin^2 z}{cos^2 z}+1}}=frac{1}{sqrt{frac{sin^2z+cos^2 z}{cos^2 z}}}=frac{1}{sqrt{frac{1}{cos^2 z}}} =sqrt{cos^2 z} =left|cos zright|$$ $$Rightarrow frac{-20}{sqrt{tan^2 frac{t}{2}+1}}=-20left|cos frac{t}{2} right|$$
    $endgroup$
    – Zacky
    Dec 5 '18 at 9:52












  • $begingroup$
    Something is wrong, because when I replace t from $ 2pi $ to 0, the circumference comes 0
    $endgroup$
    – Student123
    Dec 6 '18 at 0:47
















0












0








0





$begingroup$

$$sqrt{50-50cos x}=sqrt{50}sqrt{1 - cos x} =sqrt{50}sqrt{2 sin^2 frac{x} {2}}=10left| sinfrac{x} {2}right| $$
Can you finish now using this?






share|cite|improve this answer









$endgroup$



$$sqrt{50-50cos x}=sqrt{50}sqrt{1 - cos x} =sqrt{50}sqrt{2 sin^2 frac{x} {2}}=10left| sinfrac{x} {2}right| $$
Can you finish now using this?







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 5 '18 at 0:50









ZackyZacky

5,4981856




5,4981856












  • $begingroup$
    Did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14






  • 2




    $begingroup$
    Yes, your answer is correct. You can also simplify it to:$$frac{-20}{sqrt{tan^2 frac{t}{2}+1}} =frac{-20}{sqrt{sec^2 frac{t}{2}}} =-20left|cos frac{x} {2} right|$$ And of course you need to add $+C$. And if you differentiate it you should see that we find what I left in the answer.
    $endgroup$
    – Zacky
    Dec 5 '18 at 1:20












  • $begingroup$
    how did you simplify that?
    $endgroup$
    – Student123
    Dec 5 '18 at 8:27










  • $begingroup$
    Oh, I just realised that I used $x$ in the last part instead of $t$. To prove it I will denote $frac{t}{2}=z$ then we have: $$frac{1}{sqrt{tan^2 z+1}} =frac{1}{sqrt{frac{sin^2 z}{cos^2 z}+1}}=frac{1}{sqrt{frac{sin^2z+cos^2 z}{cos^2 z}}}=frac{1}{sqrt{frac{1}{cos^2 z}}} =sqrt{cos^2 z} =left|cos zright|$$ $$Rightarrow frac{-20}{sqrt{tan^2 frac{t}{2}+1}}=-20left|cos frac{t}{2} right|$$
    $endgroup$
    – Zacky
    Dec 5 '18 at 9:52












  • $begingroup$
    Something is wrong, because when I replace t from $ 2pi $ to 0, the circumference comes 0
    $endgroup$
    – Student123
    Dec 6 '18 at 0:47




















  • $begingroup$
    Did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14






  • 2




    $begingroup$
    Yes, your answer is correct. You can also simplify it to:$$frac{-20}{sqrt{tan^2 frac{t}{2}+1}} =frac{-20}{sqrt{sec^2 frac{t}{2}}} =-20left|cos frac{x} {2} right|$$ And of course you need to add $+C$. And if you differentiate it you should see that we find what I left in the answer.
    $endgroup$
    – Zacky
    Dec 5 '18 at 1:20












  • $begingroup$
    how did you simplify that?
    $endgroup$
    – Student123
    Dec 5 '18 at 8:27










  • $begingroup$
    Oh, I just realised that I used $x$ in the last part instead of $t$. To prove it I will denote $frac{t}{2}=z$ then we have: $$frac{1}{sqrt{tan^2 z+1}} =frac{1}{sqrt{frac{sin^2 z}{cos^2 z}+1}}=frac{1}{sqrt{frac{sin^2z+cos^2 z}{cos^2 z}}}=frac{1}{sqrt{frac{1}{cos^2 z}}} =sqrt{cos^2 z} =left|cos zright|$$ $$Rightarrow frac{-20}{sqrt{tan^2 frac{t}{2}+1}}=-20left|cos frac{t}{2} right|$$
    $endgroup$
    – Zacky
    Dec 5 '18 at 9:52












  • $begingroup$
    Something is wrong, because when I replace t from $ 2pi $ to 0, the circumference comes 0
    $endgroup$
    – Student123
    Dec 6 '18 at 0:47


















$begingroup$
Did I get the right anwser?
$endgroup$
– Student123
Dec 5 '18 at 1:14




$begingroup$
Did I get the right anwser?
$endgroup$
– Student123
Dec 5 '18 at 1:14




2




2




$begingroup$
Yes, your answer is correct. You can also simplify it to:$$frac{-20}{sqrt{tan^2 frac{t}{2}+1}} =frac{-20}{sqrt{sec^2 frac{t}{2}}} =-20left|cos frac{x} {2} right|$$ And of course you need to add $+C$. And if you differentiate it you should see that we find what I left in the answer.
$endgroup$
– Zacky
Dec 5 '18 at 1:20






$begingroup$
Yes, your answer is correct. You can also simplify it to:$$frac{-20}{sqrt{tan^2 frac{t}{2}+1}} =frac{-20}{sqrt{sec^2 frac{t}{2}}} =-20left|cos frac{x} {2} right|$$ And of course you need to add $+C$. And if you differentiate it you should see that we find what I left in the answer.
$endgroup$
– Zacky
Dec 5 '18 at 1:20














$begingroup$
how did you simplify that?
$endgroup$
– Student123
Dec 5 '18 at 8:27




$begingroup$
how did you simplify that?
$endgroup$
– Student123
Dec 5 '18 at 8:27












$begingroup$
Oh, I just realised that I used $x$ in the last part instead of $t$. To prove it I will denote $frac{t}{2}=z$ then we have: $$frac{1}{sqrt{tan^2 z+1}} =frac{1}{sqrt{frac{sin^2 z}{cos^2 z}+1}}=frac{1}{sqrt{frac{sin^2z+cos^2 z}{cos^2 z}}}=frac{1}{sqrt{frac{1}{cos^2 z}}} =sqrt{cos^2 z} =left|cos zright|$$ $$Rightarrow frac{-20}{sqrt{tan^2 frac{t}{2}+1}}=-20left|cos frac{t}{2} right|$$
$endgroup$
– Zacky
Dec 5 '18 at 9:52






$begingroup$
Oh, I just realised that I used $x$ in the last part instead of $t$. To prove it I will denote $frac{t}{2}=z$ then we have: $$frac{1}{sqrt{tan^2 z+1}} =frac{1}{sqrt{frac{sin^2 z}{cos^2 z}+1}}=frac{1}{sqrt{frac{sin^2z+cos^2 z}{cos^2 z}}}=frac{1}{sqrt{frac{1}{cos^2 z}}} =sqrt{cos^2 z} =left|cos zright|$$ $$Rightarrow frac{-20}{sqrt{tan^2 frac{t}{2}+1}}=-20left|cos frac{t}{2} right|$$
$endgroup$
– Zacky
Dec 5 '18 at 9:52














$begingroup$
Something is wrong, because when I replace t from $ 2pi $ to 0, the circumference comes 0
$endgroup$
– Student123
Dec 6 '18 at 0:47






$begingroup$
Something is wrong, because when I replace t from $ 2pi $ to 0, the circumference comes 0
$endgroup$
– Student123
Dec 6 '18 at 0:47













0












$begingroup$

Hint:



$$sqrt{50-50cos(t)}=sqrt{50}cdot sqrt{1-cos(t)}$$



and



$$sqrt{1-cos(t)}=sqrt{2}cdot|sin(t/2)| $$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14
















0












$begingroup$

Hint:



$$sqrt{50-50cos(t)}=sqrt{50}cdot sqrt{1-cos(t)}$$



and



$$sqrt{1-cos(t)}=sqrt{2}cdot|sin(t/2)| $$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14














0












0








0





$begingroup$

Hint:



$$sqrt{50-50cos(t)}=sqrt{50}cdot sqrt{1-cos(t)}$$



and



$$sqrt{1-cos(t)}=sqrt{2}cdot|sin(t/2)| $$






share|cite|improve this answer









$endgroup$



Hint:



$$sqrt{50-50cos(t)}=sqrt{50}cdot sqrt{1-cos(t)}$$



and



$$sqrt{1-cos(t)}=sqrt{2}cdot|sin(t/2)| $$







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 5 '18 at 0:52









Thomas ShelbyThomas Shelby

2,480221




2,480221












  • $begingroup$
    did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14


















  • $begingroup$
    did I get the right anwser?
    $endgroup$
    – Student123
    Dec 5 '18 at 1:14
















$begingroup$
did I get the right anwser?
$endgroup$
– Student123
Dec 5 '18 at 1:14




$begingroup$
did I get the right anwser?
$endgroup$
– Student123
Dec 5 '18 at 1:14


















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%2f3026417%2ffinding-integral-of-sqrt-50-50-cost%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

Mont Emei

Province de Neuquén

Journaliste