[Tex/LaTex] Align square root symbols in equation

Question

I have the following equation in my tex document:

\documentclass{article}
\begin{document}
  \begin{equation}
    x_{ij} = \frac{
                \sum_{t}{e_i(t)e_j(t)}
             } { 
                \sqrt{\sum_t{e_i^2(t)}} 
                \sqrt{\sum_t{e_j^2(t)}}
             }
  \end{equation}
\end{document}

The equation is printed like this:

The problem is that despite having almost the same content, the two square root symbols are rendered with a different size.

Is it possible to equalize the size of the two square root symbols?

Answer 1

\documentclass{article}
\begin{document}
  \begin{equation}
    x_{ij} = \frac{
                \sum_{t}{e_i(t)e_j(t)}
             } { 
                \sqrt{\strut\sum_t{e_i^2(t)}} 
                \sqrt{\strut\sum_t{e_j^2(t)}}
             }
  \end{equation}
\end{document}