Write FACT if the statement is correct, otherwise, BLUFF if not. (15 points)
______ 11. An ellipse is a conic which is not parallel to any generator of a right circular cone.
______ 12. The directrices are two lines outside the ellipse parallel to the major axis.
______ 13. If the foci of the ellipse are on the y-axis, then it is a horizontal ellipse.
______ 14. The foci of the ellipse are collinear with the center and the covertices.
______ 15. If the major axis is horizontal, the two latera recta are drawn vertical.
______ 16. If a2

= 16, then the length of the major axis is 4.

______ 17. The length of the major axis is equal to the sum of the distances from the two foci.
______ 18. The longer axis of symmetry is the major axis of the ellipse whose length is a.