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Problem 274: Isosceles Triangle, 80-80-20, Angles
Level: High School, SAT Prep, College geometry.

In the figure below, triangle ABC is isosceles with AB = BC. If angle B = 20 and angle CAD = 70,
prove that angle CED = 20. Try to use elementary geometry (Euclid's Elements.)

Isosceles Triangle 80-80-20, Angles 

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