# butterfly theorem

The butterfly theorem may be stated as follows: Let *M* be the midpoint of a chord *PQ* of a circle, through which two
other chords *AB* and *CD* are drawn. If *AD* intersects *PQ* at *X* and *CB* intersects *PQ* at *Y*,
then *M* is also the midpoint of *XY*. The theorem gets its
name from the shape of the resulting figure.