Question 62658
Given a point (4 ,0) and 

Equation along the "x" axis, i.e.  y = 0 


Distance between a point (x ,y) and the point ( 4 ,0) is given by

sqrt [ ( 0 -x) ^ 2  + ( 4 - y) ^2 ]  =  equal to the equation of line


sqrt [ ( 0 -x) ^ 2  + ( 4 - y) ^2 ]  =  y

Square on both sides of the baove equation, we get

[x ^ 2 + (  4 -y) ^2] = y ^ 2


Simplifying the above step we get,

x^2 + 16 + y ^2 - 8y = y^2

x ^ 2 -8y + 16 = 0

The above equation represent the set of all points equidistant from x -axis  and 
point ( 4, 0).