Chapter 7 - Applications of Trigonometry and Vectors - Section 7.4 Vectors, Operations, and the Dot Product - 7.4 Exercises - Page 332: 5

We can sketch vector $-b$ by taking the original vector $b$ and rotating it $180^{\circ}$.

We can sketch vector $-b$ by taking the original vector $b$ and rotating it $180^{\circ}$. That is, vector $-b$ points in the opposite direction as the original vector $b$.