.Mzcw.NzE5Mg

(17) And in general if a:b::b:c, then will ac = bb see § 52.

76. Hence it follows, that to find a geometric mean proportion unclear, or simply a geometric mean, or as it is often expressed a mean proportional between two quantities, you need only multiply the quantities together & extract the square root of the product. Thus if it were required to ding a mean proportional between 20 & 180: their product is 3600, the square root of which deletion unclear /deletion addition is /addition 60 the mean required; for 20:60::60:180.

77. The first term in a continued proportion is to the third in a duplicate ratio of the first to the second. For in the geometric proportion a:am::am:amm, the ratio of a to am,

is expressed by formula & the ratio of a to am is 

expressed by a/am = 1/m; but the ratio 1/m2 is duplicate of 1/m. Because formula Q.D.E.