This is drawing triangles every 10 degrees, then plotting in red the ratio of the Y value of the top corner to the X value. It then puts a dot at the tan(angle). Notice that the two dots are on top of each other because tan(angle) is actually the ratio of the length of the side opposite the angle (the Y value) to the adjacent side (the X value). If you look at the code, near the end of the repeat loop you'll see the two dots being plotted. There are 3 ratios of the lengths of sides for triangles, opposite to adjacent (named tan), which this shows, opposite to hypotenuse (named sin) and adjacent to hypotenuse (named cos). Try modifying the code to plot those other two ratios.
