00:02
Problem.
00:02
We are given the information that the focus is at zero two.
00:07
Our directrix is the line y equals negative two and then that is the equation of our parabola.
00:12
We are asked to use the distance formula here.
00:15
So if my focus is at zero two, my directrix, this line right here, y equals negative two.
00:27
If i wanted to quickly sketch out my parabola, i'm going to use one and zero here.
00:36
If i plug zero in for x squared, i would have zero times one eighth, which would just give me zero.
00:41
If i plug in one for x, i would get one eighth for y.
00:47
So that would mean that my vertex is here at the one negative one and my parabola would look something like this.
01:06
Again, with this point right here being one one eighth.
01:13
So a parabola is special because the distance between the focus and a point on the parabola is equal to the distance between that point and the directrix.
01:23
So that's what we're going to prove here with the distance formula.
01:26
So i'm going to do the distance formula, which is the square root of x two minus x one squared plus y two minus y one squared.
01:41
And i'm going to use the point one and one eighth and i'm going to use my focus...