# A Property of Angle Bisectors III

The applet below illustrates a proof of the Angle Bisector theorem suggested by Gregoire Nicollier, Sion, Switzerland. The proof is a modfication of the one submitted by Professor McWorter and applies to both internal and external angle bisectors:

$\frac{AB}{AC} = \frac{BD}{CD}.$

I leave it as a proof without words. It's a good exercise to figure out what is it about.

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