Examples of using Directrix in English and their translations into Thai
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Colloquial
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Ecclesiastic
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Ecclesiastic
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Computer
Line of the directrix.
Directrix Spellman, come quickly.
So let's call that a directrix.
The directrix is going to look like this.
Now notice, what is this directrix?
So your directrix is going to be right there.
And then you get your directrix, right?
And then our directrix is going to be 1/8 below it.
Just so you get the terminology we will call this line a directrix.
So our directrix is going to be right down here.
It's equidistant from a focus and a directrix, where this is the focus.
The directrix is going to be there, the focal point is there.
What is that focus and that directrix for this particular parabola?
Directrix, it's probably a word you have never heard before.
And then, we want to find the focus or the directrix of a parabola like this.
That's our directrix and it has the equation y is equal to k.
Locus of all points that are equidistant to a point and a directrix that it is a parabola.
This is the locus of all points that are between the directrix, y is equal to k-- well, they're equidistant to the directrix, y is equal to k, and the focus a comma b.
Well, it's just the difference in y because no matter where we are we're just going to drop down straight to the directrix.
If you just draw the focus and the directrix, you might be able to figure that out.
In the last video, we said what is the equation of the line that is equidistant between this focus and this directrix?
If we changed that ratio, if we find all of the points that are 1/2 as far away from the directrix as the focus, we start getting another conic section.
And we set that up using the distance formula to here, and then setting that equal to the distance to the line, to the directrix.
And now we should be able to use this information to figure out the actual coordinates of the focus and the directrix of what I would call the classic parabola, y is equal to x squared.
And what we want to do is we want to find all of the points in the xy-plane that are equidistant to this focus and this directrix.
In the last video, we showed that if you had a line, which we will call a directrix-- we draw the directrix.
We say we have a parabola, and we're saying that this parabola is the set of all points that's equidistant between some focus and some directrix.
And the whole point of doing all of this is just to realize that it's pretty easy to find the focus and the directrix of a parabola if you have its equation in this form.
But it's was a particular circumstance, and you don't want to have to go through this whole situation every time you have to figure out the focus or the directrix of a parabola.
And then you know the distance from the vertex to the focus, and you know the distance from the vertex to the directrix, and you're all done.