Saltire Software

Angle Bisector Theorem

The Angle Bisector Theorem provides a relationship between the sides of a triangle and the line segments the angle bisector cuts the base into.

See if you can see what the relationship is. (Note: it is not necessary to change the angle, although, you can do it if you please)

This document requires an HTML5-compliant browser.
AB
AC
θ
BD
DC
AB/BD
AC/DC

What is the relationship shown by the Angle Bisector Theorem?

Can you prove it? (try law of sines. if you aren't familiar with the law of sines, look it up!)

App generated by Geometry Expressions