If you ever came across a vector in a high-school science class, it probably looked quite simple: a little arrow you might draw on a diagram to show the motion of a train or the forces on a swinging pendulum. An arrow pointing right would cancel an arrow pointing left, or → + ← = 0. Add together two arrows pointing in the same direction, you get one twice as long: →. A rightward arrow plus an upward one? You’ve got yourself a diagonal: → + ↑ = ↗.
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