Polar curve

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For a plane curve given C by the equation f(x0,x1,x2) and a point a = (a0,a1,a2), the polar curve Pa(C) is a curve given by the equation a0f0 + a1f1 + a2f2 = 0, where fi are partial derivatives.

The intersection of C and Pa(C) is the visible contour of C from the point a, i.e., the set of points p such that the tangent at p to C contains a. (picture needed).

Some common types of polar curves include the limacon, lemniscate, rose curve, cardioid, and spiral.

See also: Polar surface

This article will be about the mathematics of polar curves. For its use in aviation see Polar curve (aviation).