# Thread: rearranging equation

1. ## rearranging equation

Hi Im a bit confused with the following
how do I rearrange the equation below so I can calculate the value of d

2. Originally Posted by scarface1
Hi Im a bit confused with the following
how do I rearrange the equation below so I can calculate the value of d

All the values which are in the denominator are multiplied to bring it to other side and all values which are in the numerator are divided to bring it to the other side. Do this for all values except $\displaystyle d$.

$\displaystyle G = \sigma \frac{\pi d^2}{4D}$

Multiplying by $\displaystyle 4D$ and divide by $\displaystyle \sigma \pi$ each side to obtain:

$\displaystyle \frac{4DG}{\pi \sigma} = d^2$

Square root both side to obtain $\displaystyle d$ on its own as a subject.

$\displaystyle d = \sqrt{\frac{4DG}{\pi \sigma}}$

3. Originally Posted by Air
Square root both side to obtain $\displaystyle d$ on its own as a subject.

$\displaystyle d = \sqrt{\frac{4DG}{\pi \sigma}}$
Since we dont know the domain of d, just to be precise:

$\displaystyle d = \pm \sqrt{\frac{4DG}{\pi \sigma}}$

4. Hi guys

Thank you so much for your help. I understand it a lot better now!