Question

if radius of curvature is equal to infinity then formula changes to​

Answer 1

Answer:

The radius of curvature of a curve at a point M(x,y) is called the inverse of the curvature K of the curve at this point: R=1K. Hence for plane curves given by the explicit equation y=f(x), the radius of curvature at a point M(x,y) is given by the following expression: R=[1+(y′(x))2]32|y′′(x)|.

Answer 2

If radius of curvature of mirror becomes infinity, i.e, it is a plane mirror..
Therefore, |v| = |u|
Hope it helps ya:)