[Tex/LaTex] Curly brace behind equations

environmentsequationspositioning

I have the following question: I like to have a big curly brace behind the equations to show that they belong together and have only one equation number.

An example without the brace would be

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{align}
\begin{split}
    x &= r\,\cos \varphi\\
    y &= r\,\sin \varphi
\end{split}
\end{align}

\end{document}

I would like to have the curly bracket behind the two equations. I saw this already in textbooks but have not found latex code for that. I guess it is very simple, but at the moment I have no clue how to do it. I was already searching for a while.

Best Answer

You could use the following, modified version of the code you've provided:

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\begin{equation}
\left.
\begin{aligned}
    x &= r\,\cos \varphi \quad\\ % use \quad as spacer between equation and right brace
    y &= r\,\sin \varphi
\end{aligned}
\right\}
\end{equation}
\end{document}

enter image description here

By the way, both the align and split environments, which you employ in your code, let users set alignment points (e.g., the equal sign) with the & symbol. Using both environments simultaneously is redundant.

Note that I've substituted equation for align, and aligned for split, in the code above because you mention that you want the equations to be associated with a single equation number. (The align environment will create separate equation numbers for each equation it encounters unless you use the \notag command, but this seems more complicated than using the aligned environment inside an equation environment.)

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