Write the definitions of S.I Supplementary units

1. Radian (rad): The radian is a unit of plane angle. It may be defined as the angle between
two radii subtended at the centre of a circle by an arc equal in length to the radius.

2. Steradian (sr): The steradian is the unit of solid angle. It may be defined as the solid
angle, which, having its vertex in the centre of a sphere, cuts off an area of the surface of
sphere equal to that of a square having sides of length equal to the radius of the sphere.

The two supplementary units are :

S.No.QuantityS.I. unitsSymbol
1.Plane angelradianrad
2.Solid angelsteradiansr

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