5

Part of 1984 Canada National Olympiad

Problems(1)

Classic: 7 real numbers

Source: Canadian Mathematical Olympiad - 1984 - Problem 5.

7

real numbers, prove that there are two of them

x,y

0\le\frac{x-y}{1+xy}\le\frac{1}{\sqrt{3}}

trigonometryinequalitiesalgebra proposedalgebra