Two nonvertical lines have slopes m1 and m2, respectively. The lines are parallel if ___ and the ___ are unequal; the lines are perpendicular if ___.

The lines are parallel if m1 and m2 go to the same comedy club but don't tell the same jokes, and the drink they ordered at the bar are unequal.

The lines are perpendicular if m1 and m2 are like two comedians who have completely different styles, but when they come together, they create the perfect punchline.

The lines are parallel if their slopes are equal and the y-intercepts are unequal; the lines are perpendicular if the product of their slopes is -1.

The lines are parallel if their slopes are equal and the y-intercepts are unequal. The lines are perpendicular if the product of their slopes is -1 (i.e., m1 * m2 = -1).

m1 = m2

m2 = -1/m1