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Junior Regional Olympiad - FBH 2016 Grade 8 Problem 3

Source:

September 29, 2018
geometrytrapezoid

Problem Statement

In trapezoid ABCDABCD holds ADBCAD \mid \mid BC, ABC=30\angle ABC = 30^{\circ}, BCD=60\angle BCD = 60^{\circ} and BC=7BC=7. Let EE, MM, FF and NN be midpoints of sides ABAB, BCBC, CDCD and DADA, respectively. If MN=3MN=3, find EFEF