

Online Geometry
Problem 4. Triangle, Quadrilateral, Angles, 120 Degrees.
Level: High School, Honors Geometry, College,
Mathematics Education
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In the figure below, AD = CD = BC, and angle
C = 2(angle A). Prove that x = 120°  angle A.
Try to use elementary geometry (Euclid's Elements.)
See
also: Art 01
Problem 42.







