Extra verification (green/red light), degeneracy cases
- Zoltán Kovács
In general diagonals of a parallelogram bisect each other.
You can change the position of points A, B and C. Then D will be always automatically constructed. In each case the green light on the top-left shows if segments AE and CE are of equal length.
- Drag points A, B and C to check whether diagonal BD indeed bisects diagonal AC.
- Find an "extremal" position set for points A, B and C to make the green light red. Explain the situation.