From the concept of optics on a curvature of a spherical mirror, the proportion for which the focal length is equivalent to half the radius of curvature is fulfilled. Mathematically this is
[tex]f = \frac{R}{2}[/tex]
Here,
f = Focal Length
R = Radius
Rearranging to find the radius we have,
[tex]R = 2f[/tex]
Replacing with our values,
R = 2(13.8cm)
R = 27.6cm
Therefore the radius of the spherical surface from which the mirror was made is 27.6cm
