A dime .334 m away from, and on the optical axis of, a concave spherical mirror produces an image on the same side of the mirror as the source. The image is .093 m away from the mirror. If the dime is moved on the axis to .229 m from the mirror, how far away from the mirror is the image now?

What is the radius of the sphere of which the mirror is a section?

i still need to know how to find the radius

1 answer

Use the mirror equation I provided in my previous answer

1/Do + 1/Di = 1/f = 2/R

Solve that for R. You won't need to solve for the focal length f.