16Hit1600
Geometry and TrigonometryVery hardAngle formed by an angle bisector

Geometry and Trigonometry practice question

In triangle ABC, angle B measures 50° and angle C measures 70°. Point D lies on side BC so that segment AD bisects angle A. What is the measure, in degrees, of angle ADB?

Answer: 100

Angle A = 60°, so angle BAD = 30°. In triangle ABD, angle ADB = 180 − 50 − 30 = 100.

Common wrong answers

If you answered 30
30 is half of angle A.
If you answered 60
60 is angle A itself.
If you answered 80
80 is angle ADC, the other angle at D.

More Geometry and Trigonometry questions

Not affiliated with the College Board. SAT is a trademark of the College Board.