Three regular polygons of six or more sides cannot form a solid angle.
Hence three will form a solid angle, that of the cube, and four will not.
If a solid angle be contained by three plane angles, any two of them are together greater than the third.
There is no telling what the web and rivets would have borne had not the solid angle irons given way at the first bend.
This appeareth plainely out of the nature of a solid angle, by the kindes of plaine figures.
Hence it is possible to form a solid angle with three, four or five regular triangles or faces.
A similar difference exists between a solid angle and an n-edge or an n-flat.
|solid angle |
A three-dimensional angle, formed by three or more planes intersecting at a common point. Its magnitude is measured in steradians, a unitless measure. The corner of a room forms a solid angle, as does the apex of a cone; one can imagine an indefinite number of planes forming the smooth round surface of the cone all intersecting at the apex. Solid angles are commonly used in photometry.