PX275 - B4a - surface of revolution

surface revolution

d A = d s y d θ = 2 π y d s

A = \int_{s_{1}}^{s_{2}} 2 π y d s

d s = \sqrt{d x^{2} + d y^{2}} = \sqrt{1 + {(\frac{d x}{d y})}^{2}} d y