When I imagine a circle($x^2+y^2=1$) and rotate it around the x axis, I get a shape of sphere.
So my question is why $(2πr)\timesπ$ and $(πr^2)\timesπ$ do not represent the area and volume of sphere.
I see that there are overlapped points especially in case of the volume, but still resulting values are too far away from the values obtained using spherical coordinates system.
What am I missing?
In this way we have some overlapping which cause an overestimation of the volume. The correct method to use this idea is based on Pappus's Centroid Theorem for the surface and volume