Construct
a line AB as a given base of the parallelogram.
2
Construct
a point M above the line AB.
3
Define
a
reflection at the point M, then construct the images of the two points
A and B by reflection on M by selecting them to get the other two
vertices of the parallelogram C and D.
4
Join
up the four points A, B, C and D to get the required parallelogram.
5
Switch
to drag mode. Pick a free element. Move it around to check your
construction.