At Orange County Choppers, Paul Teutul Junior needs to make a circular metal disk with area [math]

The radius of such a disk is inches.

To keep Paul Senior from blowing a gasket, Paul Junior must deviate from the ideal area of the disk, which is [math], by less than [math] How close to the ideal radius must the Flowjet (the machine that cuts the disk) be to maintain tranquility at OCC?

Answer = inches.

In terms of the [math] definition of [math], let [math] be the actual radius of the disk and [math] the actual area of the disk.
What is the formula for the function [math]?
What is the number [math]?
What is the number [math]?
What value of [math] is given?
What is the corresponding value of [math]?