Inner angles

The magnitude of the internal angle at the main vertex C of the isosceles triangle ABC is 72°. The line p, parallel to the base of this triangle, divides the triangle into a trapezoid and a smaller triangle. How big are the inner angles of the trapezoid?

Correct result:

A =  54 °
B =  54 °
C =  126 °
D =  126 °

Solution:

γ=72 α=β α+β+γ=180 α+α+γ=180  α=180γ2=180722=54 β=α=54=54  A=α=54=54
B=β=54=54
C+B=180 C=180B=18054=126
A+D=180  D=C=126=126



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