Answering my own question...
To get multi-line text and equations to align as you want them to, use the \begin{align} ...\end{align} pair, and place an "&" in front of the desired alignment. For example:
$$\begin{align}
&a=\sin(\theta)\\
&b = \text{abcde}\\
&z=\sqrt{x^2+y^2}\\
c=&\text{D}\\
\end{align}$$
produces the (meaningless) equation in the attachment.