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steradian
sr
SI unit of solid angle
Note 1 to entry: 1 sr is equal to the solid angle that, having its vertex at the centre of a sphere, cuts off an area of the surface of the sphere equal to the square of the radius of the sphere.
Note 2 to entry: This entry was numbered 845-01-20 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-1266 in CIE S 017:2011.