JEE Advanced2006MathematicsParabolaActual
Axis of a parabola is y=x and vertex and focus are at a distance 2 and 2 2 respectively, from the origin. Then, equation of the parabola is
Options
- A(x-y)^2=8(x+y-2)
- B(x+y)^2=2(x+y-2)
- C(x-y)^2=4(x+y-2)
- D(x+y)^2=2(x-y+2)
Correct answer
A. (x-y)^2=8(x+y-2)
Step-by-step solution
As distance of vertex from origin is 2 and focus is 2 2 . V(1,1) and F(2,2) [i.e. lying on y=x ] where, length of latusrectum aligned & =4 a, & =4 2 aligned [ where a= 2 ] By definition of parabola P M^2=(4 a)(P N) where, P N is length of perpendicular upon x+y-2=0 [i.e. tangent at vertex] array ll & (x-y)^2 2 =4 2 ( x+y-2 2 ) & (x-y)^2=8(x+y-2) array Hence, the equation of parabola is (x-y)^2=8(x+y-2) .