Answer
It could be found by finding the terminal angle of $\cos$ 2000$^{\circ}$, and then using that terminal angle to find the reference angle which would be significantly smaller, and could be used to evaluate the equation.
Work Step by Step
2000$^{\circ}$ - 5(360$^{\circ}$) = 200$^{\circ}$
200$^{\circ}$ = The terminal angle of 2000$^{\circ}$
180$^{\circ}$ - 200$^{\circ}$ = -20$^{\circ}$
-20$^{\circ}$ = The reference angle of 200$^{\circ}$
Therefore:
$\cos$ 2000$^{\circ}$ = -$\cos$ 20$^{\circ}$
-$\cos$ 20$^{\circ}$ = -0.93969262
