Angle Bisector Theorem
If a point is on the bisector of an angle, then it must be equidistant from the sides of the angle.
Statement Reasons
1. Angle AED and Angle AFD and right angles 1. def. of perpendicular lines
2. Angle AED = Angle AFD 2. Both are 90 degree right triangles
3. Angle ADE = Angle ADF 3. def. of angle bisector
4. Line AD = Line AD 4. reflexive
5. Triangle ADF = Triangle ADE 5. AAS
6. Line ED = Line DF 6. CPCTC