Chapter 7 - Applications of Trigonometry and Vectors - Section 7.4 Vectors, Operations, and the Dot Product - 7.4 Exercises - Page 332: 15

We can sketch the vector $c$ and the vector $d$ so that their initial points coincide. When we complete the parallelogram, the resultant vector through the middle of the parallelogram is the vector $c+d$.

To sketch the vector $c+d$, we can sketch the vector $c$ and the vector $d$ so that their initial points coincide. Then we can use another copy of the vector $c$ and the vector $d$ to complete the parallelogram. The resultant vector through the middle of the parallelogram is the vector $c+d$.