Three minor corrections should be sufficient to make this work for both, HTML and PDF output:
- remove the backslash before the closing bracket in
\right\)
- delete the empty line in the middle
- specify the column alignment in each
array
environment, e.g., with\begin{array}{cc}
–
$$ \left(\begin{array}{cc} 0.8944272 & 0.4472136\\ -0.4472136 & -0.8944272 \end{array}\right) \left(\begin{array}{cc} 10 & 0\\ 0 & 5 \end{array}\right) $$