PLEASE HELP (at least c)

A machinist is required to manufacture a circular metal disk with area 715cm squared
. Give your answers in exact form. Do not write them as decimal approximations.

a) What radius, x , produces such a disk?

b) If the machinist is allowed an error tolerance of ±5cm2 in the area of the disk, how close to the ideal radius in part (a) must the machinist control the radius?

c) Using the ε / δ definition of a limit, determine each of the following values in this context:

f(x)=
a=
L=
ε=
δ=