# Vertical align fractions

Is it possible to align two formulas in two lines inside a case block, that are not of the same lenght? For example, I have these two formulas and I would like to align vertically the left hand part before = and align the two fractions on the right hand part in order to occupy the same space.

\begin{cases}
E_{\theta}=\dfrac{num}{denom}\dfrac{very long num}{shorter denom}  \\
E_{\phi}=\dfrac{longer num}{denom}\dfrac{1}{long denom}
\end{cases}

• What do you mean by “occupy the same space”? – egreg Jun 7 '18 at 9:47
• Are you asking how to align the invidual \dfrac expressions? Please advise. – Mico Jun 7 '18 at 9:51
• Exactly, the two formulas are composed by two \dfracand I'd like that the two are vertically aligned the one to the other – Shika93 Jun 7 '18 at 9:55

Here are two possible solutions. Both make use of array environments. The upper solution centers both pairs of fractional terms vertically. The lower solution right-aligns the first pair of terms and left-aligns the second pair. Note that \times directives have been inserted to make sure that the readers understands how the fractional terms in a given row are supposed to be associated with each other.

\documentclass{article}
\usepackage{array,amsmath}
\newcolumntype{C}{>{\displaystyle}c}
\newcolumntype{L}{>{\displaystyle}l}
\newcolumntype{R}{>{\displaystyle}r}
\newcolumntype{z}{>{{}}c<{{}}} % for mathbin & mathrel operators
\begin{document}

\setlength\arraycolsep{0pt}

$\left\{ \begin{array}{RzCzC} E_{\theta}&=&\frac{\text{num}}{\text{denom}}&\times& \frac{\text{very very long num}}{\text{shorter denom}} \\[2ex] E_{\phi} &=&\frac{\text{longer num}}{\text{denom}}&\times& \frac{1}{\text{long denom}} \end{array} \right.$

$\left\{ \begin{array}{RzRzL} E_{\theta}&=&\frac{\text{num}}{\text{denom}}&\times& \frac{\text{very very long num}}{\text{shorter denom}} \\[2ex] E_{\phi} &=&\frac{\text{longer num}}{\text{denom}}&\times& \frac{1}{\text{long denom}} \end{array} \right.$
\end{document}