Adams' Circle
Theorem 
Monge &
d'Alembert Three Circles Theorem II with Dynamic Geometry

Miquel's
Pentagram with Dynamic Geometry.

NinePoint Center,
NinePoint Circle, Euler Line.
22 Interactive steps 
Proposed Problem 39.
Triangle, Incircle, Bisector, Cyclic Quadrilateral and angles. 
Second AjimaMalfatti Point
Interactive illustration. 
AjimaMalfatti Point
Animated angle 
Lemoine Theorem
Animated angle 
Menelaus' Theorem
Animated angle 
Triangle and Squares
18
Sangaku Problem 
Triangle and Squares
17

Blanchet Theorem
Animated angle 
Sawayama Thebault's
theorem 
Proposed Problem 33.
Triangle and quadrilateral. 
Cyclic
Quadrilateral: Ratio of the Diagonals

Problem 32.
Triangle, Cevian, Incircles, Tangents. 
Problem 31. Right Triangle, Incircle, Collinears.
Problem 30. Right Triangle, Incircle,
Inradius. 
Interactive Mind Map of the Van Hiele Model of Geometric Thought 
Problem
29.
Right Triangle, altitude, incircle and inradius. Ten conclusions. 
Equal Incircle Theorem
Animated angle 
Heron's Formula with medians 
Apollonius' Tangency Problem for Three Circles Interactive
illustration. 
Problem 29: Geometry
Help.
Facts you should know. 
Proposed Problem 27
Right Triangle, incircles and inradius. 
Proposed Problem 25
Right Triangle, altitude, incircles and inradius 
Proposed Problem 23
Right Triangle, altitude, incircles and inradii. 
Proposed Problem 22
Right Triangle, altitudes, incircles and inradii. 
Proposed problem 19
Right Triangle and Excenter 
Proposed problem 20
Right Triangle, incircles and inradii. 
Proposed problem 21
Acute triangle,
orthocenter, diameter, tangents. 