A right triangle......................from 1/2, 0 to -1, 1....................would have a hyp. of 1.8..........more or less...............3/2 for the bottom side..........along the X axis............and 1 up............1/2 the square root of 13..............which matches the 1st 3 terms of the harm ser.....1 + 1/2 + 1/3....

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Imaginary number

Description

An imaginary number is a complex number that can be written as a real number multiplied by the imaginary unit i, which is defined by its property i² = −1. The square of an imaginary number bi is −b². For example, 5i is an imaginary number, and its square is −25. Zero is considered to be both real and imaginary. Wikipedia