Question 293979
That's the equation for the volume of a sphere.
The equation can be derived in various ways, but that is always the result.
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The derivative of that is {{{4*pi*r^2}}}, which is the equation for the surface area of a sphere.  I hope that doesn't keep you awake at night.
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The area of a circle is {{{pi*r^2}}}, and the derivative of that is 2pi*r, the circumference.  Spooky, huh?