Knubic is redirecting to http://www.askamathematician.com/2013/02/q-is-it-a-coincidence-that-a-circles-circumference-is-the-derivative-of-its-area-as-well-as-the-volume-of-a-sphere-being-the-antiderivative-of-its-surface-area-what-is-the-explanation-for-this/
One moment pleace