P LANE G EOMETRY In 3D, a plane can be expressed as the set of solutions (x,y,z) to the equation ax+by+cz+d=0 ax+by+cz+d > 0 is one side of the plane ax+by+cz+d < 0 is the other side ax+by+cz+d = 0 is the plane itself ab c z x y
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