What is the equation in standard form of the parabola with a focus at (14,5) and a directrix of y= -15?

2 Answers
Dec 30, 2017

The equation of parabola is y=1/40(x-14)^2-5

Explanation:

Focus is at (14,5) and directrix is y=-15. Vertex is at midway

between focus and directrix. Therefore vertex is at

(14,(5-15)/2) or (14, -5) . The vertex form of equation of

parabola is y=a(x-h)^2+k ; (h.k) ; being vertex. Here

h=14 and k = -5 So the equation of parabola is

y=a(x-14)^2-5 . Distance of vertex from directrix is

d= 15-5=10, we know d = 1/(4|a|):. |a|=1/(4d) or

|a|=1/(4*10)=1/40 . Here the directrix is below

the vertex , so parabola opens upward and a is positive.

:. a=1/40 Hence the equation of parabola is

y=1/40(x-14)^2-5
graph{1/40(x-14)^2-5 [-90, 90, -45, 45]} [Ans]

Dec 30, 2017

(x-14)^2=40(y+5)

Explanation:

"the standard form of a parabola in "color(blue)"translated form" is.

•color(white)(x)(x-h)^2=4p(y-k)

"where "(h,k)" are the coordinates of the vertex"

"and p is the distance from the vertex to the focus"

"since the directrix is below the focus then the curve"
"opens upwards"

"coordinates of vertex "=(14,(5-15)/2)=(14,-5)

"and "p=5-(-5)=10

rArrrArr(x-14)^2=40(y+5)larrcolor(red)"equation of parabola"