Can you say what angle is made by the two red lines drawn on two sides of the cube as shown in the illustration?

i believe it to be 60 degrees.

if the edges of the cube are length 1, then the line segments are length sqrt2.
if we form a triangle by connecting the segments with a line segment diagonally along the 'bottom' of the cube, that segment will also be sqrt2.
that makes an equilateral triangle, which has interior angles of 60-60-60.

Posted by rixar on 2004-08-04 08:13:25