Question

find the slopes of the following lines y-4=0​

Answer 1

y - 4 = 0

=> y = 4 is a line parallel to x - axis, any line parallel to x-axis will have zero slope.

slope m = tan A

A is the angle between x- axis and the line. when any line is parallel to x-axis angle A = 0

therefore slope m => tan 0° => 0