Google Classroom
GeoGebraClasse GeoGebra

for intersecting lines,vertically opposite angles are equal

We can see two lines AB and DC in black color. We can freely move these four points A, B, C and D. Angle AED(α) and angle BEC(β) are also written. Move the points A, B, C and D and observe how the angles get changed.
Questions to think about 1. Compare the values of α and β, what do we observe? 2. Is it possible to get α≠β?