Properties of a trapezium

ABCD is a trapezium. Click and drag either of the blue points to change the shape of the trapezium. Observe and answer the following questions: a) How are the lengths of the diagonals related? b) How are the angles formed by the intersections of the diagonals related? c) How are the midpoints of the diagonals related?

Observe and answer the following questions: a) How are the lengths of the diagonals related? b) How are the angles formed by the intersections of the diagonals related? c) How are the midpoints of the diagonals related?