Details

Each of the three circles is tangent to the other two. The green circle is tangent to the side of the yellow isosceles triangle. The theorem states that the line from to is perpendicular to the diameter of the blue circle. You can change the position of the center of the purple circle.

Click the "configuration" button to see the triangle and circles. Click the "line AC" button to see the subject of the theorem. Click the "auxiliary points and lines" button to see the construction used in the proof of the theorem.