may be represented graphically. Starting from 0, pass in the positive direction (to the right in the figure) 3 units, then in the
i
direction 2 units, calling the sum the distance from 0 to the stopping-place.
“Of course the question will arise as to the hypotenuse being the sum of the two sides of the right-angled triangle. But the case is parallel to that mentioned in paragraph 2; it is not the sum of the absolute values, any more than is 1 the sum of the absolute values of 4 and −3; it is the sum when we define addition for numbers involving direction as well as length.
“A simple illustration from the parallelogram of forces is often used to advantage.
“Suppose a force pulling 3 lbs. to the right (+3 lbs.) and another pulling 2 lbs. upwards (+2
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lbs.); required the resultant of the two. It is evident that this is
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