MathDB

5

Part of 2003 Bulgaria Team Selection Test

Problems(1)

Prove a angular equality

Source: Bulgaria TST 2003 P5

9/8/2012
Let ABCDABCD be a circumscribed quadrilateral and let PP be the orthogonal projection of its in center on ACAC. Prove that ∠APB=∠APD\angle {APB}=\angle {APD}
Asymptotegeometrytrigonometrytrig identitiesLaw of Sinesgeometry proposed