A triangle and its polar triangle with respect to a conic are perspective.
Chasles's Polar Triangle Theorem
See also
Polar TriangleThis entry contributed by Floor van Lamoen
Explore with Wolfram|Alpha
References
Coxeter, H. S. M. The Real Projective Plane, 3rd ed. Cambridge, England: Cambridge University Press, 1993.Referenced on Wolfram|Alpha
Chasles's Polar Triangle TheoremCite this as:
van Lamoen, Floor. "Chasles's Polar Triangle Theorem." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/ChaslessPolarTriangleTheorem.html