MathDB
Easy Geometry

Source: 2024 KJMO first round

October 27, 2024
geometrycircumcircle

Problem Statement

There is a ABC\triangle ABC which C=90\angle C=90, and ABˉ=36\bar{AB}=36 On the circumcircle of ABC\triangle ABC, there is \overarc{BC} which does not include point AA. D is on \overarc{BC}. It satisfies 2×CAD=BAD2\times\angle CAD = \angle BAD E:ADˉBCˉE: \bar{AD}\cap\bar{BC} AEˉ=20 \bar{AE}=20 Find BDˉ2 \bar{BD}^2