Question

A parabola can be drawn given a focus of (1, -7) and a directrix of y = 1. Write the

Answer 1

Answer:

Step-by-step explanation:

focus (1 , -7)  ⇒ a = 1  & b = -7

y = 1 ⇒ c = 1

Equation of parabola :

(x - a)² + (y - b)² = (y - c)²

(X - 1)² + (y + 7)² = (y - 1)²

Now, expand.

x² - 2x + 1 + y² + 2*7*y + 7² = y² - 2*y*1 + 1

x² - 2x + 1 + y² - 14y + 49 = y² - 2y +1

x² - 2x + 1 + y² - 14y +  49  - y² + 2y - 1 = 0

x² - 2x  + y² - y²   - 14y + 2y   + 1 + 49 - 1 = 0

x² - 2x  - 12y + 49 = 0