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??
I'm not sure what you mean by focus and directix, but it's easy enough to convert it into a normal cartesian equation.
And from that, you should be able to get any information you want.
Why did the vector cross the road?
It wanted to be normal.
use the focus directrix form of the eqn of a parabola:
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