In mathematics, a trident curve (also trident of Newton or parabola of Descartes) is any member of the family of curves that have the formula:
xy+ax3+bx2+cx=d
Trident curves are cubic plane curves with an ordinary double point in the real projective plane at x = 0, y = 1, z = 0; if we substitute x = and y = into the equation of the trident curve, we get
ax3+bx2z+cxz2+xz=dz3,
which has an ordinary double point at the origin. Trident curves are therefore rational plane algebraic curves of genus zero.