Radii can make an angle {azimuth}| {polar angle} with polar axis.
Dihedral angles {spherical angle} are at diameter where great-circle planes intersect.
1/720 {spherical degree}| of sphere surface is solid-angle unit. One spherical degree is the birectangular spherical triangle whose third angle is one degree.
Difference {spherical excess} between spherical-polygon angle sum and plane angle sum is (n - 2) * (180 degrees), where n is number of angles.
Sphere has solid angle 4 * pi {steradian, solid angle}|.
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Date Modified: 2022.0225