Complex Analysis, Video #2. Complex Arithmetic, Methods and Geometric Interpretations, Part 2. (Complex addition in the complex plane...hint at parallelogram law)
Review: imaginary unit, complex numbers (use "Re" and "Im" notation), addition of complex numbers. Plotting complex numbers in the complex plane using ListPlot on Mathematica (Mma) and noting how, when you plot two complex numbers, their sum, and the origin, you always get a parallelogram if the complex numbers don't lie on the same line through the origin (in which case their sum would lie on that line as well). Options used for ListPlot include AxesLabel, PlotRange, PlotStyle, and AspectRatio on Mma.