Answer
$cot 1800^{\circ}= undefined$
Work Step by Step
1. What we know about 1800 degree angle
$\theta=0^{\circ}$ (because it is a co-terminal angle and values of x and y will be the same)
$x=1$
$y=0$
$r=1$
2. Substitute in:
$\cot\theta=\frac{x}{y}=\frac{1}{0}=undefined$
