Recall that in polar coordinates:
[tex](r,\theta)=(-r,\theta+\pi)\text{.}[/tex]1) Notice that:
[tex]\frac{11\pi}{6}=\frac{5\pi+6\pi}{6}=\frac{5\pi}{6}+\pi[/tex]2) Using the first equation we get:
[tex](1,\frac{5\pi}{6})=(-1,\frac{5\pi}{6}+\pi)=(-1,\frac{11\pi}{6})\text{.}[/tex]Answer: -1.