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Geometry Problem 4: Solve the Challenging Concave Quadrilateral Problem with High School Geometry.


In the figure below, ABCD is a concave quadrilateral, where AD = CD = BC, and angle C = 2 times angle A. Prove that x is equal to: 120 degrees minus angle A. Try to use elementary geometry (such as Euclid's Elements)

Geometry Problem 4. Concave Quadrilateral, Angle. Elearning

Geometry Problem 4

Concave quad it is,
AD, CD, and BC equals,
Angle C twice of A,
Prove x equals one-twenty minus A,
With Euclid's Elements, this problem we seal.

See solution below

See also:
Art 01
Problem 42.


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Last updated: Sep 19, 2014

Geometry Problem 4 Solution(s)