Mathjax rendering issue

Question

For an equation, mathjax renders like as shown in image. Please help me to find the problem and fix. In codecogs latex editor, this is rendered properly. In MathType equation editor also it displays well.

Actual code follows.

 \begin{align}f(x) &= Sin\: [\pi ]x-Sin[\pi ^{2}]x+Cos[-\pi ^{3}]x \\\\
 [\pi ] &=[3.14]=3\\\\ [\pi ^{2}]&=[9.8596]=9\\\\
 [-\pi ^{3}]&=[-9.8596]=-10 \\\\
 f(\frac{\pi }{6}) &= Sin(3\times \frac{\pi }{6})-Sin(9\times \frac{\pi }
 {6})+Cos(-10\times \frac{\pi }{6})\\\\ 
 &=Sin\frac{\pi }{2}-Sin\frac{3\pi }{2}+Cos(\frac{5\pi }{3})\\\\ 
 &= 1-\left ( -1 \right )+\frac{1}{2}\\\\
 & =2+\frac{1}{2}\\\\ 
 &=\frac{5}{2} \end{align}

Answer 1

It seems the character [ is causing some problem with align environment and MathJax.

This seems to work for me (at least on JaxEdit and http://math.stackexchange.com):

\begin{align}
    f(x) & = Sin(\pi)x - Sin(\pi^2)x + Cos(-\pi^3)*x \\
    \left[\pi\right] & = \left[3.14\right] = 3 \\ 
    \left[\pi ^{2}\right] & = \left[9.8596\right]=9 \\
    \left[-\pi ^{3}\right] & = \left[-9.8596\right]=-10 \\
    f(\frac{\pi }{6}) & = Sin(3\times \frac{\pi }{6})-Sin(9\times \frac{\pi}{6})+Cos(-10\times \frac{\pi }{6})\\
    & = Sin\frac{\pi }{2}-Sin\frac{3\pi }{2}+Cos(\frac{5\pi }{3})\\
    & = 1-\left ( -1 \right )+\frac{1}{2}\\
    & = 2+\frac{1}{2}\\
    & = \frac{5}{2}
\end{align}

Or use an equivalent symbole from one of the package that is installed with your MathJax solution