## Multiple Lines in Equations

Multiple lines in equations are handled between the delimiters \begin{align} and \end{align} with each line separated from the next with the use of '\\' at the end. Each line can be aligned at a location designated by '&' on each line.

For example, the equation:

\begin{align} & \text{if} \quad r\le 1.57\quad {{f}_{w}}=0.3 \\ & \text{if} \quad r>1.57\quad {{f}_{w}}=0.00251\ \exp \left( 5.21\ {{r}^{-0.19}} \right) \\ \end{align}

was typed as follows:
\begin{align} & \text{if} \quad r\le 1.57\quad {{f}_{w}}=0.3 \\ & \text{if} \quad r>1.57\quad {{f}_{w}}=0.00251\ \exp \left( 5.21\ {{r}^{-0.19}} \right) \\ \end{align}

The same multi-line equation can be numbered, by enclosing the whole of the "align" inside an Equation template, as shown below:

 \begin{align} & \text{if} \quad r\le 1.57\quad {{f}_{w}}=0.3 \\ & \text{if} \quad r>1.57\quad {{f}_{w}}=0.00251\ \exp \left( 5.21\ {{r}^{-0.19}} \right) \\ \end{align} (25)

was typed as follows:
{{Equation|\begin{align} & \text{if} \quad r\le 1.57\quad {{f}_{w}}=0.3 \\ & \text{if} \quad r>1.57\quad {{f}_{w}}=0.00251\ \exp \left( 5.21\ {{r}^{-0.19}} \right) \\ \end{align}|25}}