# Guldin or it's not necessary? "surface" of revolution 3

Calculus Level 5

Consider the single rectangle in $$\mathbb{R}^2$$ that passes through the points $$A = (1,2), B = (2,1), C = (4,3), D = (3,4)$$ rotating around $$x$$-axis in $$\mathbb{R}^3$$.

The volume of the surface of revolution obtained can be written as $$A\pi \text{ unit}^3$$.

Submit $$A$$.

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