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1

Part of 2000 Finnish National High School Mathematics Competition

Problems(1)

Externally tangent circles

Source: Finnish Mathematics Competition 2000, Final Round, Problem 1

11/14/2011
Two circles are externally tangent at the point AA. A common tangent of the circles meets one circle at the point BB and another at the point CC (B≠C)B \ne C). Line segments BDBD and CECE are diameters of the circles. Prove that the points D,AD, A and CC are collinear.
geometrygeometric transformationhomothetygeometry unsolved