.
    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 = 1/K. 
    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)^(3/2)) / |(y′′(x))|.
The rest is on you.
As the reference to the theory and examples, see the link
https://www.math24.net/curvature-radius/#:~:text=The%20radius%20of%20curvature%20of,%E2%80%B2%E2%80%B2(x)%7C.
https://www.math24.net/curvature-radius/#:~:text=The%20radius%20of%20curvature%20of,%E2%80%B2%E2%80%B2(x)%7C.