Whose Theorem?

Author:: GeoGebra Institute of Southern Connecticut

is an arbitrary triangle (you can move points

,

, and

around).

,

, and

are equilateral triangles.

GeoGebra Applet

INVESTIGATE:

How are , , and constructed?
What type of triangle is ?
The correct answers to investigations 1 and 2 comprise a theorem named for a famous Frenchman. Who is this Frenchman?

Adapted from material of Richard DeCesare.