# Text within an equation

I am trying to achieve the equation shown in the figure attached below

I am not getting the desired result in terms of the alignment of the text between equations and the main text.

I have tried text mode with split in equation option, but the alignment of text is not correct (First equation in the MWE below). Next (second equation in the MWE)I tried with split intertext and gather, which aligns the text, but it also aligns the equations to the left with the main text and the right brace and equation number is also screwed up.

Is there any way to achieve this?

MWE

\documentclass{article}
\usepackage{amsmath}
\usepackage{lipsum}
\begin{document}
\lipsum[1]

$$\left. \begin{split} \text{with respect to point B}\\ aP_{1}-2aN_{c}+3aP_{2} & = 0\\ \text{with respect to point C}\\ 2aN_{B}-aP_{1}+aP_{2} &=0\\ \end{split} \right\} \label{label-of-equation}$$

\begin{gather}
\left.
\begin{split}
\intertext{with respect to point $B$}
aP_{1}-2aN_{c}+3aP_{2} & = 0\\
\intertext{with respect to point $C$}
2aN_{B}-aP_{1}+aP_{2} &=0\\
\end{split}
\right\}
\label{label-of-equation}
\end{gather}
\lipsum[1]
\end{document}

The empheq package (which loads mathtools and amsmath) can help reproduce the O.P.'s image:

\documentclass{article}

\usepackage{empheq}

\usepackage{lipsum}
\begin{document}
\lipsum[2]%
\begin{empheq}[right =\mathrlap{\enspace\empheqrbrace}]{align}%
\shortintertext{with respect to point $B$: }
&aP_{1}-2aN_{c}+3aP_{2} = 0 \notag\\[-1ex]\\[-1ex]
\shortintertext{with respect to point $C$: }
&2aN_{B}-aP_{1}+aP_{2}=0\notag
\label{label-of-equation}
\end{empheq}

\lipsum[2]
\end{document}

A simple way to move the equation to the left margin is to insert the command \displayindent=-103ptbetween and \left. (Maybe you will have to play with the exact number.) Disadvantage: the number of the equation will also move to the left.

• The -103pt seems arbitrary, and probably has to change whenever the text block/page dimensions change.
– Werner
Jan 24 '15 at 15:12