# using but cannot align equation and want to show only one number of equation

I want to write these equations using the , however can't align them to the left side and want to put only one reference number for them

$$\begin{split} S=-\frac{1}{2}\rho v \delta \left(\frac{\ mu}{pF}\right)^{1/2} e \sin{\theta} \\ T = -\frac{1}{2}\rho v \delta \left(\frac{\mu}{pF}\right)^{1/2} \left( 1+e \cos{\theta}- r\alpha \left(\frac{p}{\mu}\right)^{1/2} \cos{i} \right) \end{split}$$


this is the output of my code

but i want to align my equations like in the following picture

help me thanks :)

• What you is left-aligned, or do I misunderstand what you want? – Bernard Jul 17 '19 at 14:13
• I also have some trouble understanding your question. Could you show a screenshot of the output you have now, and a mockup screenshot of the output that you want to have? – Marijn Jul 17 '19 at 14:50
• edited , the first picture is my output , the second picture is the output that i want – Quintis Jul 17 '19 at 15:16

## 2 Answers

Your code doesn't produce the image.

However, use the proper markup:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

$$\begin{split} S &= -\frac{1}{2}\rho v \delta \left(\frac{\mu}{pF}\right)^{\!1/2} e \sin\theta \\ T &= -\frac{1}{2}\rho v \delta \left(\frac{\mu}{pF}\right)^{\!1/2} \biggl( 1+e \cos\theta- r\alpha \left(\frac{p}{\mu}\right)^{\!1/2} \cos i \biggr) \\ W &= -\frac{1}{2}\rho v \delta \frac{r\alpha}{\sqrt{F}}\sin i \cos(\omega+\theta) \end{split}$$

\end{document}


Note that I changed \left( and \right) to \biggl( and \biggr) that produce correctly sized fences. Also \sin{\theta} can be more simply \sin\theta.

I also added a negative thin space to the exponents, in order not to have them too far from the parenthesis.

My humble proposal. You can replace each of your equations with a, b, c, d and e.

\documentclass[a4paper,12pt]{book}
\usepackage{amsmath}
\begin{document}
\chapter{Name}
\begin{aligned} a&= b \\ c&= d \\ e&= f \end{aligned}
\end{document}


For example:

S& =-\frac{1}{2}\rho v \delta \left(\frac{\mu}{pF}\right)^{1/2} e \sin\theta \\


instead of a&= b

• For a more systematic handling of numbering you could have a look to my answer to tex.stackexchange.com/q/470400/33514 – Jhor Jul 17 '19 at 20:56
• @Jhor Welcome :-) Thank you very much for your detailed answer. If you prefer you are authorized to edit my code. There is no problem for me. – Sebastiano Jul 17 '19 at 21:09