Question 595728
End points of diameter = (4,2) and (4,-8). 

mid point of these points = centre

Mid point = (4+4)/2 = 4,  (-8+2)/2 =-3

Mid point (4,-3)

Slope of diameter = (-8-2)/0

slope of this line is not defined. so it is a line parallel to Y axis

passes through (4,3)

so the equation will be x=4