Advanced Geometric JavaScript Applets

Some interesting, somewhat more difficult geometric configurations are presented here.

A cubic spline construction
Intersections of exterior common tangents to 3 circles
Intersections of interior common tangents of 3 circles
An isosceles triangle theorem
A theorem using the Pythagoras diagram but yielding a surprising triangle
A derived quadrilateral
Napoleon's Theorem
Circle through three points
4 special points of a triangle