24
4.
1 at the base
a cube has six faces
Do pyramids have perpendicular faces ?
24
4.
8
4
two.
7
Each lateral face is perpendicular to its lateral neighbours so that makes 4 pairs. In addition, opposite lateral faces may be perpendicular, making 6 pairs in all.
1 at the base
A pentagonal prism has only 7 faces. Each of the five lateral faces is perpendicular to the two bases: that makes 10 pairs of mutually perpendicular faces. In general, the lateral faces are not perpendicular, but four of them may be perpendicular to one or more of its neighbors - at most 4 more pairs. Still not 25!
A triangular pyramid has four faces and 2 pairs.
4, obviously.
3A cube has three pairs of parallel faces:I. Top / bottomII. Front / backIII. Left side / right side