1. use the distance formula to find the equation of a parabola with the given focus and
directrix
please show work step by step ***and please don't copy from google***
F(7,0), x = -7
Solution
P(x,y) lies on parabola iff distance of P from focus F(7,0) = distance of P from directrix x = -7
iff (x-7)^2+(y-0)^2 = (x+7)^2 (we are equating distance squares, distance from (x,y) to the line x
= -7 is distance between (x,y) and (-7,y), since line perpendicular to x = -7 is parallel to x-axis,
and thereby the foot of perpendicular from (x,y) to the line has y coordinate same)
iff y^2 = (x+7)^2-(x-7)^2
iff y^2 = 28x