25 × 18 × ·7854 = 353·43 square inches. Area required.
To find the area of a parabola, or its segment.
Multiply the base by the perpendicular height, and take two-thirds of the product for the area.
Example.—Required the area of a parabola, whose base is 20 feet, and height 12 feet.
20 × 12 = 240
⅔ of 240 = 160 square feet. Area required.
MENSURATION OF SOLIDS.
A solid is a body containing length, breadth, and thickness.
Solids are measured by cubes, whose sides are each an inch, a foot, a yard, &c., and the solidity, capacity, or content of any figure is computed by the number of such cubes as are contained in it.—Vide Cubic measure, [page 276].
A cube is a solid contained by six equal square sides.