Lesson eLearning

Find the equation of the conic with focus , directrix , and eccentricity . Determine the type of the conic.

hard 5 marks Class 11 · Mathematics · Conic Sections
Answer
(x+6)^2/36 - y^2/45 = 1 (hyperbola)

The correct answer is (x+6)^2/36 - y^2/45 = 1 (hyperbola) — Since the equation has the form , it is a hyperbola.

Step-by-step solution

  1. Apply the definition: distance to focus equals times distance to directrix: .
  2. Square both sides: .
  3. Multiply by 4 to clear fractions: .
  4. Expand and simplify: .
  5. Rearrange and complete the square for : .
  6. Obtain and divide by 180 to get the standard form: .
  7. Since the equation has the form , it is a hyperbola.
Common mistake: Squaring the distance without taking absolute value or mishandling the sign of the directrix

Concept tested: Focus-directrix – conic equation

Published · How this solution was prepared and checked

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