Solid angle of its faces is one-sixth of that, or sr. Solid angles can also be measured in square degrees (1 sr = () square degrees), in square minutes and square seconds, or in fractions of the sphere (1 sr = fractional area), also known as spat (1 sp = 4 sr). In spherical coordinates there is a formula for the differential, where is the colatitude (angle from the North pole) and is the longitude. The solid angle for an arbitrary oriented surface S subtended at a point P is equal to the solid angle of the projection of the surface S
Platonic solid by where "θ" is the dihedral angle. The midradius "ρ" is given by where "h" is the quantity used above in the definition of the dihedral angle ("h" = 4, 6, 6, 10, or 10). Note that the ratio of the circumradius to the inradius is symmetric in "p" and "q": The surface area, "A", of a Platonic solid {"p", "q"} is easily computed as area of a regular "p"-gon times the number of faces "F". This is: The volume is computed as "F" times the volume of the pyramid whose base is a regular "p"-gon and whose height is