GEOMETRY

Thus the the succe ire terms have the same ratio, progre ions 1, 2, 4, 8, 16, 32, 64, . a, a-, a^, a*, o*, a^, a^, . are geometrical; the common ratio of the first being 2, and of the second a. The general property of a geometrical progre ion is, that the product of any two terms, or the square of any one single term, is equal to the product of every other two terms taken at an equal distance before and after the former. See Progre ion. Geometrical Proportion. — Four quantities are said to be in geometrical proportion, or simply proportionals, ■when the ratio of the first to the second is equal to the ratio of the third to the fourth. Thus, if rt: 6 is equal to c:d; then the four quantities, a, b, c, d, are in geometriciU proportion. A general property of this proportion is, that the product of the two extreme terms is equal to the product of the two means. See Proportion. [s. 523]