using \begin{equation} but cannot align equation and want to show only one number of equation

Question

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

\begin{equation}
\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}
\end{equation}

this is the output of my code

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

help me thanks :)

Answer 1

Your code doesn't produce the image.

However, use the proper markup:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{equation}
\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{equation}

\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.

Answer 2

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{equation}
\begin{aligned} 
    a&= b \\
    c&= d \\
    e&= f 
\end{aligned}
\end{equation}
\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