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2

Part of 1971 Czech and Slovak Olympiad III A

Problems(1)

Necessary and sufficient condition for an angle to be right

Source: Czech and Slovak Olympiad 1971, National Round, Problem 2

7/9/2024
Let ABCABC be a triangle. Four distinct points D,A,B,ED,A,B,E lie on the line ABAB in this order such that DA=AB=BE.DA=AB=BE. Find necessary and sufficient condition for lengths a=BC,b=ACa=BC,b=AC such that the angle ∠DCE\angle DCE is right.
geometryright angle