The shell command
"/l/www/moodle/filter/tex/mimetex.linux" -e "/m/floppy/avle/moodledata/filter/tex/a490cfd5f75e062b063895d2f080fea1.gif" -- '\Large
\cos\varphi =\frac{\mathbf{N}\cdot \mathbf{k}}{\|\mathbf{N}\| \,\|\mathbf{k}\|} =
\frac{1}{\|\mathbf{N}\|}.
'
returned status = 126
Image not found!
Please try the debugging script