your name: Brooke

the level of the question: 12
who is asking the question: Student

Which conic cannot be generated by an intersection of a plane and a double napped cone?

Hi Brooke,

There is some misunderstanding here. The official definition of a conic since the time of the ancient Greeks:

a conic is the plane section of a cone. I suppose one can define a conic the way it is done in algebra -- as the graph of a second degree equation in x and y. This allows for degenerate conics. In that case, one cannot get the "degenerate" conic x 2 = 1 (consisting of a pair of parallel lines) as a section of a cone.


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