How To: Determine whether a pair of lines are perpendicular

See how to tell whether a set of lines are perpendicular to one another given their equations with this free video math lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to determine whether a pair of lines are perpendicular given their equations.