The diagonal of an isosceles trapezoid is perpendicular to the lateral side and lies on the bisector

The diagonal of an isosceles trapezoid is perpendicular to the lateral side and lies on the bisector of the acute angle of the trapezoid. Find angle with a larger base of the trapezoid.

Since, by condition, the ВD diagonal is perpendicular to AB, the AВD triangle is rectangular.

The trapezoid of AВСD is isosceles, then the angle ADС = ВAD, and since the diagonal of the ВD is also the bisector of the angle of AСD, then the angle ADВ = ВAD / 2.

In a right-angled triangle of AВD, the sum of the angles (ВAD + ADВ) = 90.

ВAD + ВAD / 2 = 90.

3 * ВAD = 180.

Angle ВAD = 180/3 = 60.

Answer: The angle for a larger base is 60.



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