The first time I was in school for electrical engineering (long story), I had a professor who had never worked in the industry. I was in her class and the topic of the day was measuring AC waveforms.

Somewhere around middle school, you learned about squaring numbers and the inverse, finding the square root of a number, but a little reminder can't hurt. You square a number when you multiply it by ...

The square root of a negative number could easily be regarded as a curious mathematical construction that has little bearing on real life. Indeed, the French polymath René Descartes gave such numbers ...