Define a function f that determines the radius of the circle in terms of the circumference of the circle.

Question

Recall that the area of a circle, A, (in square inches) is determined by the formula A=πr2 where r is the radius of the circle (in inches). The circumference of a circle, C, is determined by the formula C=2πr

 my answer-f(r)=2*pi(sqrt(A/(pi)))

Answer 1

It is sometimes very disappointing when teachers do not cause students to learn definitions, for example:

    ∏ (that is, PI) = the ratio of the circumference of a circle over the diameter of the circle

        That's why we write the circumference (C) as ∏d or 2∏r    (also, d=2r you know)

 

So, if we want to find the radius (r) of a circle as a function of the Circumference of the circle, we would write:

      r = C/(2∏)

this looks like a pretty good function:  r = f(C) = C/(2∏)

   (just take the clue  C=2∏r  and solve for r in terms of C)

Answer 2

C = (circumference of circle with radius r) = 2πr

 

f(C) = radius of circle with circumference C

 

f(C) = C/(2π)