...fractions, we have, bc — ad; (2) hence, the following principles: 1°. If four quantities are in proportion, the product of the means is equal to the product of the extremes. Conversely, if we divide both members of (2) by cq, we have, - = - ; or, a : b : : c : d ; hence, ac...

...angle : find the area. SECTION X. 1. Define ratio and proportion. Shew that when four numbers are in proportion, the product of the means is equal to the product of the extremes. 3. State as precisely as possible your view« as to the value of Mental Arithmetic simply asan Educational...

...proportion is said to be transformed by division. PROPOSITION II. THEOREM. If four quantities are in proportion, the product of the means is equal to the product of the extremes. Assume the proportion, a : b :: c : d, whence - = - ; . . . (1) Multiplying both members of (1) by...

...last terms of a proportion are called the Extremes, and the second and third terms the Means. In any proportion the product of the means is equal to the product of the extremes. Thus, in the proportion 4 : 8 :: 12 : 24, 8x 12 = 4 x 24. ORAL EXERCISES. 1. If 2 pounds of butter...

...fourth terms of a proportion are called the extremes, and the second and third the means. 106. In a proportion the product of the means is equal to the product of the extremes. Let a : b = с : d a с 6 = 5 Clearing of fractions, ad^bc A proportion is an equation ; and making...

...the diameter is a mem proportional between the segments of the diameter). Then tiCl = MCXCN, §259 (the product of the means is equal to the product of the extremes). QEF GEOMETRY. BOOK IV. PROPOSITION XXVI. PROBLEM. 359. To construct a parallelogram equivalent to a...

...have equal denominators ; hence, their numerators are equal, that is, 5 x 8 = 2 x 20 ; in this case the product of the means is equal to the product of the extremes. But we can reason in like manner on any proportion ; hence, we have the following principle : 1°....

...numerator by the other denominator, the products are equal. Hence, iu every proportion, PRINCIPLE I. — The product of the means is equal to the product of the extremes. If multiplying either the means or extremes together produces the same product, dividing this product...

...circumference to the diameter is a mean proportional between the segments of the diameter). aXb, §259 (flu product of the means is equal to the product of the extremes). QEF 355. COROLLARY 1. A square may be constructed eqxiivalent to a triangle, by taking for its side...

...preceding illustration may be derived the following principles : 1. When four general numbers form a proportion, the product of the means is equal to the product of the extremes. 2. A missing extreme may be found by dividing the product of the means by the given extreme. 3. A missing...