# How I make brackets in LaTeX?

How I make this brackets and the formula below in LaTeX?

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Use two cases environments. – Bernard Mar 29 at 22:43

Since arrays are vertically centred, set two next to one another:

\documentclass{article}

\begin{document}

$\setlength{\arraycolsep}{0pt}% Remove inter-column gap \renewcommand{\arraystretch}{1.2}% Space out equations \left\{\begin{array}{ r l } \sum F_x & {}= m \times a_n \\ \sum F_y & {}= m \times a_t \end{array}\right.\kern-\nulldelimiterspace \quad\leftrightarrow\quad \left\{\begin{array}{ r l } T - m g \cos\theta & {}= m \times a_n \\ - m g \sin\theta & {}= m \times a_t \end{array}\right.\kern-\nulldelimiterspace$

\end{document}

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\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}

\begin{cases} \Sigma F_\mathrm{x} = m \times a_n \\ \Sigma F_\mathrm{y} = m \times a_t \end{cases} \leftrightarrow \ \ \begin{cases}\! \begin{aligned} T - mg\cos\theta &= m \times a_n \\ {}- mg\sin\theta &= m \times a_t \end{aligned} \end{cases}

\left\{\! \begin{aligned} \Sigma F_\mathrm{x} &= m \times a_n \\ \Sigma F_\mathrm{y} &= m \times a_t \end{aligned}\right. \ \ \leftrightarrow \ \ \left\{\! \begin{aligned} T - mg\cos\theta &= m \times a_n \\ {}- mg\sin\theta &= m \times a_t \end{aligned}\right.

\end{document}


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While this gets the desired affect, I disagree semantically with the use of the cases environment. There aren't any "cases" in the equation. Why not \left\{\begin{aligned}...\end{aligned}\right.? – Matthew Leingang Mar 29 at 23:09
aligned should be prepended with \! or may be with etoolbox \AtBeginEnvironment{aligned}{\!}. – Manuel Mar 29 at 23:27
@MatthewLeingang - Good point, I added that option too. – AboAmmar Mar 29 at 23:42