Constructing a Parallelogram with a Given Center*

Construction Algorithm
1 Construct a point M as a center of the parallelogram.
2 Construct two concentric circles with two different radii (MA and MB) centered at M.
3
Construct a straight line passes through M and A.
4 Generate the intersection point between the line MA and the circle whose radius MA at C.
5 Construct another line through M and B and generate its intersection point with the circle whose radius MB at D.
6 Join up the four points A, B, C, and D to get the required parallelogram.
7 Switch to Move Mode. Pick a free element. Move it around to check your construction.
Construction Theorem
A parallelogram is a quadrilateral, in which diagonals bisect each other.
Please enable Java for an interactive construction (with Cinderella).

*Center of the parallelogram is the intersection point of its diagonals.