I'm developing a software for a stainless steel plant, and I need to calculate the diameter of steel coils so the software assigns a position inside a deposit according to the size of the coil.
I have access to a lot of data from the coil, and tried thinking of a way to calculate using the inner hole diameter and the length and thickness of the steel strip.
In a research I've found this formula:
L = 3,141[(D2/2)² - (D1/2)²]/T
Where
L = Length of the coil
D1 = Diameter of the inner hole
D2 = Diameter of the coil
T = Thickness of the material
But in the software I have to put in this format:
D2 = (formula)
I'm no good with math, how can I "convert" the formula to suit my needs?
Best Answer
What you need to do is called changing the subject of the formula. $$\begin{align} L = \frac{3,141\left[(D2/2)^2 + (D1/2)^2\right]}{T}\\ \\ \hline\\ \text{Multiplying by}\; \frac{T}{3,141}\; \text{on both sides}:\frac{TL}{3,141} &= \left[(D2/2)^2 + (D1/2)^2\right]\\ \text{Adding} \;(D1/2)^2 \;\text{on both sides}:\frac{TL}{3,141}+ (D1/2)^2 &= \left[(D2/2)^2 \right]\\ \text{Taking square roots on both sides}:\sqrt{\frac{TL}{3,141}+ (D1/2)^2 }&= \sqrt{\left[(D2/2)^2 \right]}=D2/2\\ \text{Multiplying both sides by}\; 2:2\times\sqrt{\frac{TL}{3,141}+ (D1/2)^2 }&=D2\\ \end{align}$$