[size=200]As we move our lines around, what do you notice about the slopes?[br][br][br][br]   [size=150]Opposite sign & Flipped fraction[br][br][br][/size][/size][size=200]This is called the [b]negative reciprocal.[br][br][br][br][/b]When comparing the slopes of two perpendicular lines, they are negative reciprocals of each other. [b][br][br][br][/b][/size][size=200][br][/size]