Latex Math Equation Input

Question

I am having issues inserting math equations into my Latex paper. This is my current equation

\begin{equation}
\beta = \frac{ \frac{2}{\pi}\int_0^\arcsin(\frac{\frac{t}{2}}{l_bulk})l_bulk\cos(\theta)d(\theta)+\int_arcsin(\frac{\frac{t}{2}}{l_bulk})^(\frac{\pi}{2}) \frac{(\frac{t}{2})d(\theta)}{tan(\theta)} }{ \frac{2}{\pi}\int_0^(\frac{\pi}{2}) (l_bulk)\cos(\theta)d(\theta) }
\end{equation} 

however I keep getting this error. My trouble shooting so far has not helped.

! Missing { inserted
<to be read again>
            \mathop

The issue is on the last part of the equation apparently

....c{\pi}{2}) (l_bulk)\cos(\theta)d(\theta) }

Answer 1

You have to find yourself an editor that can help with brace matching:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
  \beta = \frac{%
      \displaystyle\frac{2}{\pi}
      \int_0^{\arcsin\bigl(\frac{t/2}{l_{\text{bulk}}}\bigr)} l_{\text{bulk}}\cos\theta \, \mathrm{d}\theta 
      + \int_{\arcsin\bigl(\frac{t/2}{l_{\text{bulk}}}\bigr)}^{\frac{\pi}{2}} \frac{t \, \mathrm{d}\theta}{2\tan\theta}
    }{\displaystyle \frac{2}{\pi}\int_0^{\frac{\pi}{2}} l_{\text{bulk}}\cos\theta \, \mathrm{d}\theta }
\end{equation} 
\end{document}