The numbers , , , are the members of the ; and are the extreme members and and are the middle members. The number is called the fourth proportional of the numbers , and .
The product of the extreme members of the is equal to the product of the middle members.
i.e., the middle members can be swapped.
if the do not vanish.
If any three members of a are known, then the fourth member may be determined (often by using the first property).
In (2), the number is called the third proportional of and .
|Date of creation||2014-02-23 21:37:10|
|Last modified on||2014-02-23 21:37:10|
|Last modified by||pahio (2872)|