###### Answer: d. x^2 = -8y

If p > 0 the parabola with equation = (opening to the right) has … The point C is located on the directrix (which is not shown to minimize clutter). The point B is the midpoint of the line segment FC. Deductions. Measured along the axis of symmetry the vertex A is equidistant from the focus F and from the directrix . According to the intercept theorem since C is on the directrix the y …

Mon Oct 22 2001 14:30:00 GMT-0400 (Eastern Daylight Time) ยท Alternatively one can define a conic section purely in terms of plane geometry: it is the locus of all points P whose distance to a fixed point F (called the focus ) is a constant multiple (called the eccentricity e) of the distance from P to a fixed line L (called the directrix ).For 0 < e < 1 we obtain an ellipse for e = 1 a parabola and for e > 1 a hyperbola.

Locus (mathematics) – Wikipedia

Locus (mathematics) – Wikipedia

Hyperbola – Wikipedia

Hyperbola – Wikipedia

Parabola : the set of points equidistant from a fixed point ( the focus ) and a line ( the directrix ). Hyperbola: the set of points for each of which the absolute value of the difference between the distances to two given foci is a constant. Ellipse: the set of points for each of which the sum of the distances to two given foci is a constant; Oth…