Express the volume of a sphere as a simplified function of its circumference?

Responses (3)

c = 2πr

r = c/(2π)

v = (4/3)πr^3

v = (4/3) (π) (c/(2π))^3

v = (4/3) (c^3)/(8π^2)

v = (1/6) (c^3)/(π^2)

Votes: +0 / -0

circumference c := 2 * pi * r
volume v := 4/3 * pi * r^3

Express v as a function of c: f(c) = v
Obviously the two definitions (of c and v) have the same structure. The main difference is the exponent of r. So, let's cube c:

c^3 = (2 * pi * r)^3 = 8 * pi^3 *r^3.

Now we've settled the transformation for r. Dividing by pi² reduces the exponent of pi to 1. And dividing 8 by 6 yields 4/3. And the combined expression is:

v = f(c) = c^3 / (6 * pi²)

Votes: +0 / -0

c = 2πr
V = 4/3πr^3
= 2/3 (2πr) r^2
= 2/3 c r^2

Votes: +0 / -0