Double
Cone
A geometric figure made up of two right
circular cones placed
apex to apex as shown below. Typically a double cone is considered
to extend infinitely far in both directions, especially when working
with conic sections and degenerate
conic sections.
Note: The graph of the equation z2 = x2 + y2 is a standard way
to represent a double cone. That is the equation for the image
below.

Double Cone
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