1. The side of a square equals the square root of its area.

2. The area of a square equals the square of one of its sides. 8. The diagonal of a square equals the square root of twice the square of its side.

4. The side of a square is equal to the square root of half the square of its diagonal.

5. The side of a square equal to the diagonal of a given square contains double the area of a given square.

6. The area of a rectangle equals its length multiplied by its breadth.

7. The length of a rectangle equals the area divided by the breadth; or, the breadth equals the area divided by the length.

8. The side or end of a rectangle equals the square root of the sum of the diagonal and opposite side to that required, multiplied by their difference.

9. The diagonal in a rectangle equals the square root of the sum of the squares of the base and perpendicular.

10. The solidity of a cube equals the area of one of its sides, multiplied by the length or breadth of one of its sides.

11. The length or breadth of a side of a cube equals the cube root of its solidity.

12. The capacity of a 12-inch cube equals 7.4784 United States gallons.

Surfaces and Solidities of the Regular Bodies, each of whose Boundary Lines is 1.

No. of Sides.

Names.

Surfaces.

Solids.

4

Tetrahedron.

1.7321

01179

6

Hexahedron.

6.

1.

8

Octahedron.

3.4641

0.4714

12

Dodecahedron.

20.6458

7.6631

20

Icosahedron.

8.6608

21817

The tabular surface multiplied by the square of one of the boundary lines equals the surface required; or,

The tabular solidity multiplied by the cube of one of the boundary lines equals the solidity required.