Evaluate the horizontal parabola
y2 = -12x
Determine coordinates of the focus:
Since our x coefficient of -12 is negative
The parabola opens left
horizontal parabola equation
y2 = 4cx
4c = -12
Divide each side by 4:
| 4c | |
| 4 |
| = |
| -12 |
| 4 |
c = -3
Our focus is (-3,0)
Determine directrix equation:
Directrix is in the form x = c, so we have x = -3
Common Core State Standards In This Lesson
HSG.GPE.A.2
What is the Answer?
Our focus is (-3,0)
How does the Parabolas Calculator work?
Free Parabolas Calculator - Determines the focus, directrix, and other related items for a parabola.
This calculator has 1 input.
This calculator has 1 input.
What 5 formulas are used for the Parabolas Calculator?
standard horizontal parabola equation is y2 = 4cx
standard vertical parabola equation is x2 = 4cy
If the x coefficient is negative, then parabola opens left
If the x coefficient is positive, then parabola opens right
standard vertical parabola equation is x2 = 4cy
If the x coefficient is negative, then parabola opens left
If the x coefficient is positive, then parabola opens right
What 4 concepts are covered in the Parabolas Calculator?
- directrix
- line in a parabola not through the focus
- focus
- fixed point on the interior of a parabola used in the formal definition of the curve
- parabola
- a plane curve which is approximately U-shaped
- parabolas
