MathDB
<BKC=<CDB if MA x CD = MB x LD Puerto Rico OMCC TST 2018.3

Source:

September 16, 2021
equal anglesgeometry

Problem Statement

Let MM be the point of intersection of diagonals ACAC and BDBD of the convex quadrilateral ABCDABCD. Let KK be the point of intersection of the extension of side ABAB (beyondAA) with the bisector of the angle ACDACD. Let LL be the intersection of KCKC and BDBD. If MA⋅CD=MB⋅LDMA \cdot CD = MB \cdot LD, prove that the angle BKCBKC is equal to the angle CDBCDB.
Back to ProblemsView on AoPS