AP EAMCET2003MathematicsParabola
The equation of the parabola with focus (0,0) and directrix x+y=4 is
Options
- Ax^2+y^2-2 x y+8 x+8 y-16=0
- Bx^2+y^2-2 x y+8 x+8 y=0
- Cx^2+y^2+8 x+8 y-16=0
- Dx^2-y^2+8 x+8 y-16=0
Correct answer
A. x^2+y^2-2 x y+8 x+8 y-16=0
Step-by-step solution
Given focus of parabola is S(0,0) . Equation of directrix is x+y=4 Let P(x, y) be any point on the parabola. Now, S P^2=P M^2 (x-0)^2+(y-0)^2= [ x+y-4 1+1 ]^2 x^2+y^2= (x+y-4)^2 2 2 x^2+2 y^2=x^2+y^2+16+2 x y-8 x-8 y x^2+y^2-2 x y+8 x+8 y-16=0