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A pyramid rises 'h' cm from a square base of side 'a' cm to a ridge parallel to one of the base's sides, and is the same length too. What is 'h' if the volume of the pyramid is half of that of a cube of side 'a'?

Solution

✅ Correct Option: 3

The solid is a wedge: square base a×aa\times a, top a ridge of length aa at height hh. By the prismatoid rule, V=h6(Abottom+4Amid+Atop)=h6(a2+4⋅a22+0)=ha22V=\frac{h}{6}(A_{bottom}+4A_{mid}+A_{top})=\frac{h}{6}(a^2+4\cdot\frac{a^2}{2}+0)=\frac{ha^2}{2}. Setting equal to a32\frac{a^3}{2} gives h=ah=a.

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