The diagonals AC and BD of the trapezoid are the bisectors of the angles BAD and ABC

The diagonals AC and BD of the trapezoid are the bisectors of the angles BAD and ABC, respectively. Angle CBD = 70 Find the angle BAC.

Since BD is the bisector of the angle ABC, then the angle ABD = CBD = 70.

At the trapezoid, the bases are parallel, then the angle ADB = CBD = 70 as criss-crossing angles at the intersection of parallel lines AD and BC secant BD.

In triangle ABD, angle BAD = (180 – ABD – ADB) = (180 – 70 – 70) = 40.

AC, by condition, is the bisector of the angle BAD, then the angle BAC = BAD / 2 = 40/2 = 20.

Answer: The value of the angle BAC is 20.



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