Step 1
Given; A plane intersects only one nappe of a double-napped cone such that it is parallel to the generating line and it does not contain the vertex of the cone.
Which conic section is formed?
Step 2
We know that when a slicing of a double nape cone is done such that the plane intersects one nape of a double-napped cone such that the plane is not perpendicular to the axis and is not parallel to the generating line then an ellipse is formed.
( If the plane passes just one nape of a cone and is perpendicular to the axis then a circle is obtained.
and if a plane passes through just one nappe of a cone and is parallel to the generating line and it does not contain the vertex of the cone then a parabola is obtained )
Thus the answer is;
[tex]Parabola[/tex]