focus at (-2,0) directrix the line x=2

User Icon for Damon Damon answered
9 years ago

I already took the subject. You try.

User Icon for Damon Damon answered
9 years ago

This is a pure cookbook question and just follow the procedure in your text. We are here to help if you get stuck, not to do it for you.

User Icon for Damon Damon answered
9 years ago

eg

https://www.khanacademy.org/math/algebra2/conics_precalc/parabolas_precalc/v/using-the-focus-and-directrix-to-find-the-equation-of-a-parabola

User Icon for Explain Bot Explain Bot answered
11 months ago

To find the equation of the parabola with a focus at (-2,0) and a directrix at x=2, we can start by understanding the definition of a parabola.

A parabola is a set of all points that are equidistant from the focus and the directrix.

For this problem, the focus is at (-2,0) and the directrix is the line x=2. The directrix is a vertical line since it has a constant x-coordinate.

To find the equation of the parabola, we first need to find the distance between a point (x, y) on the parabola and the focus (-2,0). We'll call this distance "d".

Using the distance formula, the distance d between a point (x, y) and the focus (-2,0) is given by:

d = sqrt((x - (-2))^2 + (y - 0)^2)
= sqrt((x + 2)^2 + y^2)

We also need to find the distance between a point (x, y) on the parabola and the directrix x = 2. We'll call this distance "d'".

Since the directrix is a vertical line with x = 2, the distance d' between a point (x, y) and the line x = 2 is equal to the difference between the x-coordinate of the point and the x-coordinate of any point on the directrix. In this case, we can use the x-coordinate of the point on the directrix as 2. So,

d' = |x - 2|

Now, according to the definition of a parabola, these distances should be equal. Therefore, we have:

sqrt((x + 2)^2 + y^2) = |x - 2|

Squaring both sides of the equation, we get:

(x + 2)^2 + y^2 = (x - 2)^2

Expanding and simplifying, we have:

x^2 + 4x + 4 + y^2 = x^2 - 4x + 4

Simplifying further, the x^2 terms cancel out, giving:

4x + 4 + y^2 = -4x + 4

Rearranging the terms, we have:

8x + y^2 = 0

So, the equation of the parabola with a focus at (-2,0) and a directrix at x=2 is 8x + y^2 = 0.