The chords [math]DE[/math] and[math]CB[/math] are two unrelated chords in the circle. The points [math]H[/math] and [math]F[/math] are the midpoint of [math]DE[/math] and [math]CB[/math] respectively.[br]There are perpendicular bisectors set on the points [math]H[/math] and [math]F.[/math]