Trigonometry (10th Edition)

$tan(-900^{\circ}) = 0$
Since each full rotation is $360^{\circ}$, the angle $-900^{\circ}$ is in the same position as $-900^{\circ}+n\times 360^{\circ}$ for any integer $n$. When $n = 3$: $\theta = -900^{\circ}+n\times 360^{\circ}$ $\theta = -900^{\circ}+(3)(360^{\circ})$ $\theta = 180^{\circ}$ For this angle, we can use the point (-1, 0). x = -1 y = 0 r = 1 We can find the value of $tan(-900^{\circ})$: $tan(-900^{\circ}) = \frac{y}{x}$ $tan(-900^{\circ}) = \frac{0}{-1} = 0$