Answer
0.5
Work Step by Step
Since cosine is an even function, $\cos(-x)=\cos(x)$.
Therefore, $\cos(-60^{\circ})=\cos(60^{\circ})$.
$60^{\circ}$ is a special trigonometric angle, where the value of $\cos(60^{\circ})$ is 0.5.
Therefore, $\cos(-60^{\circ})=0.5$.