u/Express-Distance421

I tried to figure out how to calculate the surface area of a sphere. The way I imagined was to take the circumference of a circle that dissects the middle of the sphere, then multiply it by half of the circumference: 2πr • 2πr/2 = 2(πr)^2, which makes sense to me. But it's wrong: you actually have to multiply the circumference by the diameter, which doesn't make sense.