Question 601873
the figure formed is a parallelogram (actually, a Varignon Parallelogram)


a diagonal of a quadrilateral divides the quadrilateral into two triangles.
___ in each of the triangles; connecting the midpoints of the sides (which are sides of the parallelogram)
generates a line parallel to the base (which is the diagonal of the parallelogram)
___ since the two triangles have the same base (the diagonal), the "midlines" are parallel


this is also true for the other diagonal; giving two pairs of opposite parallel sides (a parallelogram)