Problem 46.
Angles, Triangle, 15 Degrees. Level: High School, SAT
Prep, College

The figure shows an obtuse triangle
ABC (angle B is the obtuse angle), D is the
midpoint of AB, the measure of angle BCD
is 30 degrees and the measure
of angle BAC is double the measure of angle ACD. Prove that the
measure of angle ACD is 15°.
.