# Diagonal of a cube

#### Two triangular sections of a cube cut its diagonal into 3 parts as shown
below. Is the diagonal cut into 3 equal parts? Is the diagonal perpendicular
to the triangular sections? Try to drag a figure to get a better view for tackling
this problem.

*applet created with Cabri
3D, your browser will handle the applet when you install a full or evaluated
version of the software*

*press right mouse button and drag to freely rotate the entire figure*

This question is suggested by Mr. Yuen Wah Kong and discussed in a workshop
on April 29, 2006, organised by the Hong Kong Association for Science and Mathematics
Education.