Question

define radius of curvature of a spherical mirror find the nature and the focal length of a spherical mirror of radius of curvature + 24 centimetre​

Answer 1

Those behind, negative. The distance from the pole to the center of curvature is called (no surprise, I hope) the radius of curvature (r). The distance from the pole to the focal point is called the focal length (f). The focal length of a spherical mirror is then approximately half its radius of curvature.