Cos -420° = …? Cos -480° = …? By Admin ReiPosted on December 5, 2022 Cos -420° = …? Cos -480° = …? 0.5-0.5 :))))))))))))))) Cos x =cos (x+360)cos-420 = cos(-60)=1/2 cos-480 = cos-120 = -1/2