Find the equation of the parabola with focus at (0, -3) and directrix y = 3.

Practice Questions

Q1
Find the equation of the parabola with focus at (0, -3) and directrix y = 3.
  1. x^2 = -12y
  2. x^2 = 12y
  3. y^2 = -12x
  4. y^2 = 12x

Questions & Step-by-Step Solutions

Find the equation of the parabola with focus at (0, -3) and directrix y = 3.
  • Step 1: Identify the focus and directrix. The focus is at (0, -3) and the directrix is the line y = 3.
  • Step 2: Calculate the distance between the focus and the directrix. The distance is 3 - (-3) = 6.
  • Step 3: Determine the value of p. Since the focus is below the directrix, p is negative. Therefore, p = -3.
  • Step 4: Use the standard equation of a parabola that opens downwards, which is x^2 = 4py.
  • Step 5: Substitute p into the equation. Since p = -3, we have x^2 = 4 * (-3) * y.
  • Step 6: Simplify the equation. This gives us x^2 = -12y.
  • Parabola Definition – A parabola is defined as the set of all points equidistant from a focus and a directrix.
  • Focus and Directrix – Understanding the relationship between the focus, directrix, and the parameter p is crucial for deriving the equation of a parabola.
  • Standard Form of Parabola – The standard form of a vertical parabola is given by x^2 = 4py, where p is the distance from the vertex to the focus.
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