I am not sure how to work solve this problem.

Cot

^{-1}( -1/2) = tan^{-1}( -2) = - 63 .43° = 296.57° / The way you wrote that is what it reads . Arc whose or 180° - 63.43 Cot is -1/2 . Why don't you place (/) for divided by 2. Maybe it is Cot

^{-1}( -1) /2 ,then Cot

^{-1}( -1) / 2 = - π/4 * 1/2 =- π/8 , or 3π/4