Compute $(\cos 185^\circ + i \sin 185^\circ)^{54}.$
I recognize this expression as the polar form of a complex number. I can rewrite it as $e^{185^\circ i}$ using Euler's formula. To raise it to the 54th power, I can use the rule that $(e^{a})^b = e^{ab}$ for any complex numbers $a$ and $b$. So, $(\cos 185^\circ + i \sin 185^\circ)^{54} = e^{185^\circ i \cdot 54} = e^{9990^\circ i}$. Now, I want to simplify this expression by finding an equivalent angle that is between 0 and 360 degrees. I can do this by dividing 9990 by 360 and finding the remainder. 9990 divided by 360 is 27 with a remainder of 270. So, 9990 degrees is the same as 270 degrees in the standard position. Therefore, $e^{9990^\circ i} = e^{270^\circ i}$. Finally, I can convert this back to the rectangular form of a complex number using Euler's formula again. $e^{270^\circ i} = \cos 270^\circ + i \sin 270^\circ = -i$. So, the final answer is -i. 