 Let "C" be defined in homogeneous coordinates by "f"("x, y, z") = 0 where "f" is a homogeneous polynomial of degree "n", and let the homogeneous coordinates of "Q" be ("a", "b", "c").Define the operator
Then Δ"Q""f" is a homogeneous polynomial of degree "n"−1 and Δ"Q""f"("x, y, z") = 0 defines a curve of degree "n"−1 called the "first polar" of "C" with respect of "Q".If "P"=("p", "q", "r") is a non-singular point on the curve "C" then the equation of the tangent at "P" is 
In particular, "P" is on the intersection of "C" and its first polar with respect to "Q" if and only if "Q" is on the tangent to "C" at "P".