[Math] Volume of a Square-based Pyramid

geometryvolume

I've read previous answers that state that the volume of a pyramid is $\frac{1}{3}$ (base $\times$ height). One way to visualize the volume of a square-based pyramid is to envision a cube where every surface is the base of a pyramid. There would be 6 congruent pyramids in the cube and therefore, the volume of any one pyramid would be $\frac{1}{6}$ the volume of the cube. Therefore shouldn't the volume of the pyramid be $\frac{1}{6}$ (base $\times$ height), not $\frac{1}{3}$ (base $\times$ height)? Just a little confused and would appreciate any insight.

Best Answer

If we call the length of each side of your cube x, then the height of each of the six enclosed pyramids would be x/2. So the volume of each pyramid would be given by:
$$V=\frac{1}{3}\times basearea\times height=\frac{1}{3}\times x^2\times \frac{x}{2}=\frac{x^3}{6}$$
So everything is consistent. :)

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