# Pascal's mystic hexagon

If a hexagon *ADBFCE* (not necessarily
convex) is inscribed in a conic section (in
particular a circle), then the points of intersections of opposite sides
(*AD* with *FC*, *DB* with *CE* and *BF* with *EA*) are collinear. This line is called the **Pascal
line** of the hexagon. A special case is when the conic degenerates
into two lines; the theorem still holds but is then usually called **Pappus'
theorem**.