A conic is a two dimensional object. It is the set of all those points whose distance from a fixed point F is a constant times (e) its distance from a fixed straight line L.The fixed point F is called the focus, the fixed straight line is called the directrix and the fixed ratio is called the eccentricity of the conic.
If the focus is F(x_{1},y_{1}) , directrix is ax+ by + c = 0 and the eccentricity is e then √[(x  x_{1})^{2} + (y  y_{1})^{2}] =e (ax + by + c)/[√(a^{2} + b^{2})] When the focus does not lie on the conic we get nondegenerate conics. The shape of the conic depends on the value of e.

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