# Re-arranging formula

• Mar 4th 2013, 06:20 AM
raldam
Re-arranging formula
Hi guys I've been doing a dynamics problem and I am currently on the last little bit.

see attached
• Mar 4th 2013, 07:38 AM
raldam
Re: Re-arranging formula

• Mar 4th 2013, 07:41 AM
Plato
Re: Re-arranging formula
Quote:

Originally Posted by raldam

But, I will not open that file.
Are you not able to type out the question?
• Mar 4th 2013, 07:44 AM
raldam
Re: Re-arranging formula
Yer is there anyway to insert an equation, theres a few brackets, square roots and divides to type out and its difficult using the typical keyboard and people will probably get confused.

thanks

raldam
• Mar 4th 2013, 07:47 AM
raldam
Re: Re-arranging formula
-200(r-0.42r/√(r^2+〖0.3〗^2 ))=-108r

iv tried to copy and paste an equation from word, if that makes any sense to you ?
• Mar 4th 2013, 08:08 AM
Plato
Re: Re-arranging formula
You need to learn to use LaTeX

If it $-200\left(r-\frac{0.42r}{\sqrt{r^2+(0.3)^2}}\right)=-108r$
[TEX] -200\left(r-\frac{0.42r}{\sqrt{r^2+(0.3)^2}}\right)=-108r [/TEX] is the above code.
• Mar 4th 2013, 08:10 AM
raldam
Re: Re-arranging formula
arr ryt thanks for that, well yes that is the equation that I need to try and re-arrange to make r the subject.

I've been trying for ages and keep getting complex formula, I keep getting the feeling though that it is quite simple
• Mar 4th 2013, 08:20 AM
Plato
Re: Re-arranging formula
Quote:

Originally Posted by raldam
arr ryt thanks for that, well yes that is the equation that I need to try and re-arrange to make r the subject.
I've been trying for ages and keep getting complex formula, I keep getting the feeling though that it is quite simple

If $r\ne 0$ then that reduces to $\frac{84}{\sqrt{r^2+.09}}=92$
• Mar 4th 2013, 08:22 AM
raldam
Re: Re-arranging formula
thanks for your help its much appreciated, but is that the furthest it can reduce to ?

from the equation you posted is there anyway to obtain a value for r ?

thanks
• Mar 4th 2013, 09:36 AM
raldam
Re: Re-arranging formula
ignore the previous elementary question, Iv obtained my value for r

if you could, could you explain how you simplified the expression ?

thanks

rob