Kite
This shape has been constructed so that when the vertices A, C and D are moved, it is always a kite.
Try moving the vertices, what changes? What stays the same?
Now draw the diagonals by selecting the segment tool and left-clicking on A and C and then B and D.
Select the point tool and put a point, E, on the intersection point of the two diagonals.
Measure the angle between DE and EC.
What do you notice about the angle DEC as the vertices are moved?
Acknowledgements: http://www.lsp.open.ac.uk/geometry/
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