IMG_20190305_112758.jpg Sr plz solve it If the focus of the parabola is (-2,-1) and the equation of directrix is x+y=3. Then the coordinates of vertex are:

Answers (1)

@Mannika

Focus of parabola is (-2,-1)

equation of Directrix =  x + y = 3

vertex of the parabola is the mid-point of the line segment joining the focus to the intersection point of the axis and directrix

 

 The equation of the axis is x-y=\lambda\: \: i.e.\: \: -2-(-1)=\lambda \Rightarrow \lambda = -1

as axis is perpendicular to directrix and axis is passing via (-2, -1)

x-y+1=0

Point D is the intersection of Directrix and Axis (1, 2)

Thus V can be calculated

V is the midpoint of S and D

Let (h , k) be vertex.

Then 

\\h=\frac{-2+1}{2}\:\:,\:\:k=\frac{-1+2}{2}\\(h,k)=(\frac{-1}{2},\frac{1}{2}) 

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