On my website, to insert mathematics you have to use LATEX. For instance, let's say we wish to insert math within a sentence such as $q_{\rm rad}$ is equal to $\epsilon A \sigma T^4$. This can be done by typing \$q_{\rm rad}\$ is equal to \$\epsilon A \sigma T^4\$. Or, if you wish to display an equation by itself out of a sentence such as: $$ q=-\frac{\Delta T}{\sum_{i=1}^4 R_i} $$

$$ q=-\frac{\Delta T}{\sum_{i=1}^4 R_i} $$

An integral: $$ \epsilon=\int_{x=0}^L \left( \frac{x}{5}-\frac{x^2}{2} \right) dx $$

Greek symbols are generally written the way they are pronounced. Thus, $\theta$, $\xi$, $\psi$ can be written as \$\theta\$, \$\xi\$, and \$\psi\$ respectively. Capital Greek letters are written by uppercasing the first letter. Thus, $\Psi$, $\Theta$, and $\Xi$ are typeset as \$\Psi\$, \$\Theta\$, and \$\Xi\$. If you wish to write an equation with an equation number as follows: \begin{equation} F=ma \tag{23a} \label {eqn:newton} \end{equation}