x² = 4py (or y² = 4px for the horizontal case); note that p = the distance from the vertex to the focus = the distance from the vertex to the directrix

now, mathsyperson has already done most of the work!

take x² = 16y = 4(4y), so we see p = 4.

this means our parabola (with vertex (0,0) ) has focus (0, 4) and directrix y = -4

]]>x=8t

t=x/8

y=4t²

y=4(x/8)²

y=4(x²/64)

y=x²/16

And from that, you should be able to get any information you want.

]]>i needed help for parametrics,,

here's a sample question,,,

A parabola has parametric equations x=8t and y=4t^2

Find the coordinates of its focus and equation of its directix.

can somebody help me on this??

]]>