*The following is an excerpt from the chapter LaTeX Questions Answered in Pressbooks Guide: A reference for open textbook authors using Pressbooks by Arianna Cheveldave*

For our purposes, “brackets” refers to (parentheses), [square brackets], {curly brackets}, and〈angle brackets〉, as well as |vertical bars or pipes| and ||double pipes||.

There may be times when you want your brackets to appear larger than the standard size, such as when you have brackets around a fraction. Luckily, it is very easy to make your brackets match the size of whatever they are trying to contain.

Use the commands `\left`

and `\right`

to create brackets that will resize themselves to match what they surround.

For example, say you want to put parentheses around a fraction. If you use regular parentheses, the expression looks like this:^{[1]}

As you can see, the expression isn’t properly contained by the parentheses. Here’s what it looks like when you write `\left(`

and `\right)`

around the expression:

Just like that, the parentheses have resized themselves to fit around the fraction.

These dynamic brackets are not always necessary: if your bracketed expression is just a few alphanumeric characters, regular brackets will probably work just fine. But these commands are very useful for when you have a larger expression that you’d like to contain in brackets.

See the following table to learn how to write all the different kinds of brackets.

Bracket | LaTeX Markup | Rendered |
---|---|---|

(Parentheses) | `(a-b)` | (a−b) |

[Square brackets] | `[a-b]` | [a−b] |

{Curly brackets} | `\{a-b\}` | {a−b} |

〈Angle brackets〉 | `\langle a-b \rangle` | ⟨a−b⟩ |

|Vertical bars or pipes| | `|a-b|` | |a−b| |

||Double pipes|| | `\|a-b\|` | ∥a−b∥ |

Now let’s see how to write each type of dynamic bracket:

Bracket | LaTeX Markup | Rendered |
---|---|---|

(Parentheses) | `\left(\dfrac{a}{b}\right)` | (ab) |

[Square brackets] | `\left[\dfrac{a}{b}\right]` | [ab] |

{Curly brackets} | `\left\{\dfrac{a}{b}\right\}` | {ab} |

〈Angle brackets〉 | `\left\langle\dfrac{a}{b}\right\rangle` | ⟨ab⟩ |

|Vertical bars or pipes| | `\left|\dfrac{a}{b}\right|` | ∣∣ab∣∣ |

||Double pipes|| | `\left\|\dfrac{a}{b}\right\|` | ∥∥ab∥∥ |

For those types of brackets that require a command of their own and can’t just be written as is — such as the curly brackets, which must be written as `\{x\}`

— the syntax of the `\left`

and `\right`

commands can start to look a little confusing, especially when combined with other commands.

Just remember that the syntax goes `\left`

, *symbol for the opening bracket*, `\right`

, *symbol for the closing bracket*.

### Learn more:

- LaTeX Questions Answered: How do I Create an Array Using LaTeX?
- LaTeX Questions Answered: How Do I Cross Something Out?

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- You can right-click this expression and go to
**Math Settings > Math Renderer > Plain Source**and then back to**Common HTML**to switch between seeing the original LaTeX markup and the expression in display form. ↵