Complex Numbers
Complex numbers are very important for mathmeticians and engineers alike. However, the two use slightly different terminologies. Mathmeticians use "i" to denote an imaginary number, but electrical engineers use "j" to symbolize an imaginary number since "i" is used for current (specifically electron current since its a lower case "i").
As denoted below, "j" represents a -1 inside of a square-root.
Imaginary Number $ \Rightarrow j = sqrt(-1) $
Euler's Formula: $ e^{jt} = cos(t) + j*sin(t) $
