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A parabola can be drawn given a focus of (0, 2) and a directrix of y = 0. Write the

equation of the parabola in any form.

1 Answer

3 votes

Given:

Focus of a parabola = (0,2)

Directrix: y=0.

To find:

The equation of parabola.

Solution:

The equation of parabola is


y=(1)/(4p)(x-h)^2+k ...(i)

where, (h,k) is vertex, (h,k+p) is focus, y=k-p is directrix.

Focus :
(h,k+p)=(0,2)

On comparing both sides, we get


h=0


k+p=2 ...(ii)

On comparing y=k-p and y=0, we get


k-p=0 ...(iii)

Adding (ii) and (iii), we get


2k=2


k=1

Putting k=1 in (ii).


1+p=2


p=2-1


p=1

Putting h=0, k=1 and p=1 in (i).


y=(1)/(4(1))(x-(0))^2+(1)


y=(1)/(4)x^2+1

Therefore, the equation of required parabola is
y=(1)/(4)x^2+(1).

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