Question

Two lines are perpendicular. if one line has a slope of 0, what is the slope of the other line?

Answer 1

If two lines are perpendicular, then one line is an opposite reciprocal of the other. Since one line has a slope of 0, the opposite reciprocal of 0 would be -0/0, but any number over 0 is described as undefined, so the slope of the other line is undefined.