MathDB
Area Ratio

Source:

December 22, 2005
geometryratiotrigonometryAMCAIMEnumber theoryrelatively prime

Problem Statement

In triangle ABC,AB=30,AC=6,ABC, AB=\sqrt{30}, AC=\sqrt{6}, and BC=15.BC=\sqrt{15}. There is a point DD for which AD\overline{AD} bisects BC\overline{BC} and ADB\angle ADB is a right angle. The ratio Area(ADB)Area(ABC) \frac{\text{Area}(\triangle ADB)}{\text{Area}(\triangle ABC)} can be written in the form m/n,m/n, where mm and nn are relatively prime positive integers. Find m+n.m+n.