COMES IN THREE / Book, letterpress+laser print

1 A triangle is one of the basic shapes of geometry: a polygon with three corners or vertices and three sides or edges which are line segments.

2 Right Angled Triangle
Obtuse Triangle
Acute Triangle

3 The three dimensions are commonly called length, width, and depth (or height), although any three directions can be chosen, provided that they do not lie in the same plane. Three-dimensional space is a geometric model of the physical universe in which we live