## Trigonometry 7th Edition

The equivalent trigonometric form of $-11 + 2i$ is $5\sqrt{5}cis169.70^\circ$ or $5\sqrt{5}(cos169.70^\circ + isin169.70^\circ)$.
For $-11 + 2i$, the absolute value is $\sqrt{(-11)^2 + 2^2} = 5\sqrt{5}$ and $\theta = arctan(\frac{2}{-11}) = 169.70^\circ$, since $-11 + 2i$ is in the 2nd quadrant. Therefore, the equivalent trigonometric form of $-11 + 2i$ is $5\sqrt{5}cis169.70^\circ$ or $5\sqrt{5}(cos169.70^\circ + isin169.70^\circ)$.