The sum of the angles A and B of trapezoid ABCD is three times the angle C. Find the angle D.

univerkov | August 15, 2021 | education

The sum of the angles of the trapezoid with its lateral sides is 180, then the angle BAD + ABC = 180.

By condition, the angle BCD = (BA + ABC) / 3 = 180/3 = 60.

Then the sought angle ADC = (180 – BCD) = (180 – 60) = 120.

Answer: The value of the angle D is equal to 120.

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