This corresponds to what is known as vector addition in the plane,where directed line segments(vectors)are added together, top to tail(see Figure 13). We begin at the origin, which has coordinates of(0,0), and in this example we lay down our first arrow from there to the point(2,1). To add the number represented by(1,3),we go to the point(2,1), and draw an arrow that represents moving 1 unit right in the horizontal direction(that is the direction of the real axis), and 3 units up in the direction of the vertical(the imaginary axis). We end up at the point with coordinates(3,4). In much the same way, we can define subtraction ofcomplex numbers by subtracting the real and imaginary parts so that, for example,(11+7i)-(2+5i)=9+2i.This can be pictured as starting with the vector(11,7), and subtracting the vector(2,5), to finish at the point(9,2).