If a depressed quartic equation has two positive and two negative roots, then they determine the coordinates of the endpoints of two chords of a circle whose extensions intersect perpendicularly at a point outside the circle, the radius of which depends exclusively on the coefficients.
If a depressed quartic equation has two positive and two negative roots, then they determine the coordinates of the endpoints of two chords of a circle whose extensions intersect perpendicularly at a point outside the circle, the radius of which depends exclusively on the coefficients.