MathDB

3

Part of 1968 Swedish Mathematical Competition

Problems(1)

sum of squares of sides of a quadrilateral >= sum of squares of diagonals

Source: 1968 Swedish Mathematical Competition p3

3/21/2021
Show that the sum of the squares of the sides of a quadrilateral is at least the sum of the squares of the diagonals. When does equality hold?
geometryGeometric Inequalities