MathDB

9

Part of 1986 IMO Longlists

Problems(1)

Prove that AD + DB = BC

Source:

8/28/2010
In a triangle ABCABC, ∠BAC=100∘,AB=AC\angle BAC = 100^{\circ}, AB = AC. A point DD is chosen on the side ACAC such that ∠ABD=∠CBD\angle ABD = \angle CBD. Prove that AD+DB=BC.AD + DB = BC.
geometry unsolvedgeometry