Question

What is plane angle
What is solid angle

Answer 1

Answer:

Plane angle is the angle subtended at the centre of a circle by an arc of length equal to its radius. Unit-radian(rad).

rad=arc/radius=l/r

Solid angle is the angle subtended at the centre of a sphere by a surface of the sphere equal in area to that of a square having each side equal to the radius of the sphere.Unit-Steradian(sr)

sr=surface area /radius ^2

Answer 2

See the above attachment

Hope it helps you