mersenneforum.org  

Go Back   mersenneforum.org > New To GIMPS? Start Here! > Homework Help

Reply
 
Thread Tools
Old 2011-04-10, 13:44   #1
Baztardo
 
Apr 2011

3 Posts
Default Need help with an integral

Hi there! New to this forum and not good at math.. I wonder if anyone of you could help me with this matter?


The Integrand is:

pi (t-6)
P(t)= A sin _______ +B
12


The Integral is:

a

/
| P(t)dt
/

b


The following facts are known:

A=0.56
B=0.28
a=4
b=20

Thank you guys!

/Baz
Baztardo is offline   Reply With Quote
Old 2011-04-10, 15:48   #2
Christenson
 
Christenson's Avatar
 
Dec 2010
Monticello

5×359 Posts
Default

I don't understand P(t), which I believe to be A * sin( X ) + B, where X is (t*pi-6)/12. Please confirm, also confirm that your interval of integration (a to b) is going backwards, that is, a > b, so dt is negative. Once we have that, the result will be straightforward.
Christenson is offline   Reply With Quote
Old 2011-04-10, 19:12   #3
Baztardo
 
Apr 2011

3 Posts
Default

Hi there!

It´s pretty hard for me to explain. Perhaps I missplaced this question. I havent been to school for ages and I´m trying to solve this one in order to get som coordinates. I could explain the original problem:

The formula above is edited by a person trying to solve it. Perhaps your more helped by the one originally made?

pi (t-6)
P(t)= A sin +B
12

b
/
| P (t)
/
a

As before:

A = 0,56
B = 0,28
a = 4
b = 20

I have this facts:

N 57 43.Y00
E 012 54.X6Y

By solving above integral Y and X should appear.

The answer to the matter is a decimalnumber where Y is the numbers after the decimal "roughly". And X is half the number before the decimal.

Englisg is myc second languagae, I hope you understand a little more than before :)
Baztardo is offline   Reply With Quote
Old 2011-04-10, 19:56   #4
Mathew
 
Mathew's Avatar
 
Nov 2009

5368 Posts
Default

\int_{b}^aA\sin\left(\frac{\pi(t-6)}{12}\right)+B dt what I understood from Baz's post


\int_{a}^bA\sin\left(\frac{t\pi-6}{12}\right)+B dt what Christenson wrote

Let us look at Christenson's equation without the points

\int_{}A\sin\left(\frac{t\pi-6}{12}\right)+Bdt

Break this into two integrals

\int_{}A\sin\left(\frac{t\pi-6}{12}\right)dt+\int_{}Bdt

Let us do the harder integral first

\int_{}A\sin\left(\frac{t\pi-6}{12}\right)dt

A is a constant and can be placed outside of the integral

A\int_{}\sin\left(\frac{t\pi-6}{12}\right)dt

Next is an u-substitution

let u=\frac{t\pi-6}{12}

then du=\frac{\pi}{12}dt

Therefore dt=\frac{12}{\pi}du

Substitute the values

A\int_{}\frac{12}{\pi}\sin\left(u\right)du

Again since \frac{12}{\pi} is a constant move it out of the integral

Now you have

A\frac{12}{\pi}\int_{}\sin\left(u\right)du

Which is

-A\frac{12}{\pi}\cos\left(u\right)

replace the u for what was substituted

-A\frac{12}{\pi}\cos\left(\frac{t\pi-6}{12}\right)

Now do the second integral

\int_{}Bdt =Bt

The whole equation is

-A\frac{12}{\pi}\cos\left(\frac{t\pi-6}{12}\right)+Bt

Evaluating from a to b i.e. \int_{a}^b it would be the following

\left(-A\frac{12}{\pi}\cos\left(\frac{b\pi-6}{12}\right)+B*b \right)-\left(-A\frac{12}{\pi}\cos\left(\frac{a\pi-6}{12}\right)+B*a\right)

Entering in all the values =6.25624
Mathew is offline   Reply With Quote
Old 2011-04-10, 20:28   #5
Batalov
 
Batalov's Avatar
 
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3

9,059 Posts
Default

In 'Homework Help' forum, the usual thing to do would be to give hints, not a complete solution. One doesn't learn anything by simply copying the solution and turning it in.
Batalov is offline   Reply With Quote
Old 2011-04-10, 20:47   #6
Baztardo
 
Apr 2011

310 Posts
Default Thanks!

Thank you so much for helping me out with this one Mathew!!

And as a respond to moderator. I wrote above that this might be places in wrong forum since i dont intend learning the steps from the answer, this is way way way beyond my current skills in mathematics. And second it wasn´t a homework task, rather some problemsolving task inside the geocaching community.

Best wishes all of you!

/Baz
Baztardo is offline   Reply With Quote
Old 2011-04-10, 22:17   #7
Christenson
 
Christenson's Avatar
 
Dec 2010
Monticello

34038 Posts
Default

In Baz' defense, he did state that he wasn't doing homework in the classical sense. Mr Stene, thanks for the nice formatting.

Batalov, is my number theory homework, given to me by R.D Silverman (reading the literature and ensuring that I actually understand it, no grading involved) more appropriate here or under Factoring? I'm thinking about things like incremental QS, which may or may not work.
Christenson is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Integral Variation flouran Information & Answers 6 2009-07-20 20:00
please help with an integral Andi47 Homework Help 3 2009-05-13 17:49
Challenging Integral Primeinator Homework Help 9 2008-12-23 16:40
Impossible Integral Unregistered Homework Help 5 2008-03-08 20:05
Many CAS not able to solve integral nuggetprime Miscellaneous Math 1 2007-06-26 22:04

All times are UTC. The time now is 22:03.

Thu Jul 9 22:03:13 UTC 2020 up 106 days, 19:36, 0 users, load averages: 1.12, 1.27, 1.38

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.