MathDB
2014 Guts #19: Bisectors in a Trapezoid

Source:

April 21, 2014
geometrytrapezoid

Problem Statement

Let ABCDABCD be a trapezoid with ABCDAB\parallel CD. The bisectors of CDA\angle CDA and DAB\angle DAB meet at EE, the bisectors of ABC\angle ABC and BCD\angle BCD meet at FF, the bisectors of BCD\angle BCD and CDA\angle CDA meet at GG, and the bisectors of DAB\angle DAB and ABC\angle ABC meet at HH. Quadrilaterals EABFEABF and EDCFEDCF have areas 2424 and 3636, respectively, and triangle ABHABH has area 2525. Find the area of triangle CDGCDG.