MathDB

2

Part of 1975 USAMO

Problems(1)

Four Points in Space

Source: 1975 USAMO Problem 2

3/15/2010
Let A,B,C, A,B,C, and D D denote four points in space and AB AB the distance between A A and B B, and so on. Show that AC^2\plus{}BD^2\plus{}AD^2\plus{}BC^2 \ge AB^2\plus{}CD^2.
inequalitiesgeometryparallelogram