MathDB

1

Part of 2002 Junior Balkan MO

Problems(1)

Isosceles triangle and point P on the circumcircle

Source: JBMO 2002, Problem 1

10/29/2005
The triangle ABCABC has CA=CBCA = CB. PP is a point on the circumcircle between AA and BB (and on the opposite side of the line ABAB to CC). DD is the foot of the perpendicular from CC to PBPB. Show that PA+PB=2ā‹…PDPA + PB = 2 \cdot PD.
geometrycircumcircletrigonometrytrig identitiesLaw of Cosines