How to find the volume of a tetrahedron

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ACT Math › How to find the volume of a tetrahedron

Questions 1 - 3

1

What is the volume of a regular tetrahedron with an edge length of 6?

Explanation

The volume of a tetrahedron can be solved for by using the equation:

$V= \frac{a^3}{6\sqrt{2}}$

where is the measurement of the edge of the tetrahedron.

This problem can be quickly solved by substituting 6 in for .

$V=\frac{6^3}{6\sqrt{2}}=\frac{216}{6\sqrt{2}}=\frac{36}{\sqrt{2}}$

${\color{Blue} V=25.5}$

2

Find the volume of a tetrahedron if the side length is $\frac{1}{6}$ .

$\frac{\sqrt2}{2592}$

$\frac{\sqrt2}{1296}$

$\frac{\sqrt2}{216}$

$\frac{\sqrt2}{16}$

$\frac{3\sqrt2}{2}$

Explanation

Write the equation to find the volume of a tetrahedron.

$V=\frac{a^3}{6\sqrt2}$

Substitute the side length and solve for the volume.

$V=\frac{(\frac{1}{6})^3}{6\sqrt2}= \frac{1}{216}\left(\frac{1}{6\sqrt2}\right)= \frac{1}{1296\sqrt2}$

Rationalize the denominator.

$V=\frac{1}{1296\sqrt2} \cdot \frac{\sqrt2}{\sqrt2}= \frac{\sqrt2}{1296\cdot 2} = \frac{\sqrt2}{2592}$

3

Find the volume of a regular tetrahedron if one of its edges is $\sqrt[3]{6}:cm$ long.

$\frac{\sqrt2}{2};cm$

$\sqrt6:cm$

$2\sqrt6:cm$

$4\sqrt3:cm$

$2\sqrt3:cm$

Explanation

Write the volume equation for a tetrahedron.

$V=\frac{e^3}{6\sqrt2}$

In this formula, stands for the tetrahedron's volume and stands for the length of one of its edges.

Substitute the given edge length and solve.

$V=\frac{(\sqrt[3]6:cm)^3}{6\sqrt2} = \frac{6:cm^3}{6\sqrt2}= \frac{1}{\sqrt2}:cm$

Rationalize the denominator.

$\frac{1}{\sqrt2}:cm\cdot \frac{\sqrt2}{\sqrt2} = \frac{\sqrt2}{2}:cm$

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