This section is from the book "The English And American Mechanic", by B. Frank Van Cleve. Also available from Amazon: The English And American Mechanic.
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.
 
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