# How to solve 4/3 sin(x) = x

choob

## The Attempt at a Solution

those above steps imo are unnecessary, all i need to know is how to solve 4/3(sin theta)=theta, thanks in advance!

## Answers and Replies

Mentor

Two things:
1. Is your equation 4/3 * sin(theta) = theta or is it 4/[3 sin(theta)] = theta?
2. You are not going to be able to solve your equation, whichever one it is, by algebraic means. The best you can do is to get an approximate solution.

Mentor

The link you gave is broken, so I don't know what you meant to show me. In any case, what I said in post 2 still applies.

choob

its not broken, all you have to do is click on the address bar and press enter, as if you were typing the url in.

Homework Helper

The link you gave is broken, so I don't know what you meant to show me. In any case, what I said in post 2 still applies.
choob is actually right, you have to do something like copying and pasting the URL instead of just following the link. The site is probably trying to prevent direct linking.

Anyway, the PDF file doesn't change anything - there is no analytic solution. You would need to use a graphing calculator or a computer to find the answer. (There's probably some sort of series expansion trick or something you could use to get a good approximation by hand)

Homework Helper

If it's 4/3 * sin(theta) = theta you can find one pretty obvious solution.

Last edited:
astarmathsand

freeexampapers has had a lot of bandwidth problems. We welcome direct linking and plan to have enough bandwidth to allow this.

icystrike

If it's 4/3 * sin(theta) = theta you can find one pretty obvious solution.

Hi Cyosis ! I took some time looking and pondering of the possible solution and i could not figure it out , I hope you can provide me of the partial solution. Thank you.

Дьявол

Can somebody explain what's the task?

icystrike

Can somebody explain what's the task?

solve for theta

icystrike

i tried using maclaurin's series and i manage to work out with the answer of 1.28 but i guess it is rather tedious.

Homework Helper

i tried using maclaurin's series and i manage to work out with the answer of 1.28 but i guess it is rather tedious.

Well you could use the Newton-Raphson iterative method and find an approximation.

icystrike

Well you could use the Newton-Raphson iterative method and find an approximation.

Yes indeed Newton Raphson method can solve and it is similar to taylor'series.
Is there any other method to solve this question algebraically?

Last edited:
Homework Helper

No.
Yes, I was also quite dissappointed to hear that such a simple result such as the one you have presented has no means of being algebraically solved; but what can you do...