cos(100°) = -cos(80°) = -0.173648... cos(260°) = cos(180°+80°) = -0.173648... cos(260°) = cos(360°-80°) = cos(80°) = 0.17648... sin(190°) = cos(190°-90°) = cos(100°) = -cos(80°) = -0.173648...