# Chapter 5 Blocks

## 5.1 Equations

Here is an equation.

\[\begin{equation} f\left(k\right) = \binom{n}{k} p^k\left(1-p\right)^{n-k} \tag{5.1} \end{equation}\]

You may refer to using `\@ref(eq:binom)`

, like see Equation (5.1).

## 5.2 Theorems and proofs

Labeled theorems can be referenced in text using `\@ref(thm:tri)`

, for example, check out this smart theorem 5.1.

**Theorem 5.1 **For a right triangle, if \(c\) denotes the *length* of the hypotenuse
and \(a\) and \(b\) denote the lengths of the **other** two sides, we have
\[a^2 + b^2 = c^2\]

Read more here https://bookdown.org/yihui/bookdown/markdown-extensions-by-bookdown.html.

## 5.3 Callout blocks

The R Markdown Cookbook provides more help on how to use custom blocks to design your own callouts: https://bookdown.org/yihui/rmarkdown-cookbook/custom-blocks.html