Copy the vectors in the figure and use them to draw the following vectors.
$$\begin{array}{ll}{\text { (a) } a+b} & {\text { (b) } a-b} \\ {\text { (c) } \frac{1}{2} a} & {\text { (d) }-3 b} \\ {\text { (e) } a+2 b} & {\text { (f) } 2 b-a}\end{array}$$