# regular tetrahedron

## Volume of regular tetrahedron of given length of edges

**Problem**

Determine the volume of a regular tetrahedron of edge 2 ft.

A. 1.54 ft^{3} |
C. 1.34 ft^{3} |

B. 1.01 ft^{3} |
D. 0.943 ft^{3} |

## 016 Radius of the sphere circumscribing a regular triangular pyramid

**Example 016**

Find the area of the surface and the volume of the sphere circumscribed about a regular tetrahedron of edge 25 cm. See Figure 015.

## 014 Water poured into a jar of marbles

**Example 014**

A boy who had discovered that 20 mm marbles fitted snugly into the bottom of a cylindrical jar, dropped in a fourth on top of the three and poured water enough into the jar to just cover them. How much water did he use?