around the clock symmetries

The triangle (with pink, green & yellow vertices) is reflected in four lines, giving seven more triangles.
  • Check you follow how the triangles are related. Where are the invisible 'mirror lines'?
  • Move the vertices (pink, green & orange) to reshape the triangle. Note what you see ...
  • Now move the slider. What's going on? Cad atá ar siúl in aon chor?