A community for students. Sign up today!
Here's the question you clicked on:
 0 viewing

This Question is Closed

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0\[\int\limits_{2\sqrt2}^{4}\frac{ 1 }{ (t^3)\sqrt(t^21)dt }\]

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0so, I know how to do the entire problem, but, when it comes to plugging in the cos(4) and cos(2root2) i get lost.

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0dw:1360033290591:dw

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0You plugged everything in correctly, I think maybe you just made a tiny boo boo at the end. See how you're squared secant that you're left with is in the `denominator`?

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0Oh the limits? yah let's not forget that the original limits were in terms of `t`. We can't plug those into our result. We have 2 options. Plug the limits into our original substitution that we made, to find new limits of integration. `Or` we can backsubstitute and plug the t values in.

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0lets find t now, thats where Im lost

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0the other problem i had was real easy, root 2 and 2

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0now im not sure how to use these weird ones

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0\[\large t=\sec \theta\]The lower limit is \(2\sqrt2\). giving us,\[\large \frac{2}{\sqrt2}=\sec \theta\] Which is a special angle, maybe it just doesn't look like it :)\[\large \frac{2}{\sqrt2}=\frac{1}{\cos \theta} \theta \qquad \rightarrow \qquad \cos \theta = \frac{\sqrt2}{2}\]

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0dw:1360034188203:dw

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0ahhhh! algebra bites me in the retrice

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0Solution looks good so far :)

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0dw:1360034363382:dw

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0Umm if I'm remembering my angles correctly, I think that's at \(\dfrac{\pi}{4}\). Sine and Cosine both measure sqrt2/2 when theta is pi/4.

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0Doesn't sound familiar? :D

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0hmm now im lost on the 4

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0\[\large 4=\sec \theta \qquad \rightarrow \qquad \cos \theta=1/4\]Hmmmmm..

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0\[\large \cos \theta=\left(\frac{1}{2}\right)^2\]Hmm no I don't think that's going to get us in the right direction...

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0\[\large \cos \theta=1/4 \qquad \rightarrow \qquad \theta=\arccos\left(\frac{1}{4}\right)\]I think we would have to leave it like this.

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0dw:1360034799626:dw

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0Hmm I'm not quite sure what you did there :o

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0not sure if that is legal, i multiplied both sides by sec^2/sec^2

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0But it looks like you canceled how a `secant` and a `secant squared` somehow :o

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0ya thats dumb my bad

dfresenius
 one year ago
Best ResponseYou've already chosen the best response.0dw:1360035089559:dw

zepdrix
 one year ago
Best ResponseYou've already chosen the best response.0no :c i dont think that works either. I'm pretty sure we have to leave it as the arccosine.
Ask your own question
Ask a QuestionFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.