Math symbols
About us
Contact us
Site map
Search The Site
   Program of Lessons
 Study Guide
 Topics of problems
 Tests & exams
www.bymath.com Study Guide - Arithmetic Study Guide - Algebra Study Guide - Geometry Study Guide - Trigonometry Study Guide - Functions & Graphs Study Guide - Principles of Analysis Study Guide - Sets Study Guide - Probability Study Guide - Analytic Geometry Select topic of problems Select test & exam Rules Price-list Registration


Proportion. Crosswise lied terms. Ratios.
Overturned ratios. Derived proportions.

Proportion is an equality of two ratios. From a proportion   follows:
ad = bc (cross products are equal). Inversely, from ad = bc the next proportions follow:  

All these proportions and some others can be received from the original proportion
 a / b = c / d   by the next rules:

Crosswise lied terms of any proportion can be changed by places.

Ratios in any proportion can be changed to overturned ones.

Derived proportions .  If  then the next so called derived proportions, received from the original, also take place:

All these and a lot of other proportions can be united by the two base formulas:

where m, n, k, l – any numbers.

E x a m p l e :   If   m = n = k = 1,   l = 0,  then we receive:


| Home | About us | Links | Contact us |

Copyright © 2002-2007 Dr. Yury Berengard.  All rights reserved.