>>745
cos(50°) = √(1-a^2)
cos(130°) = cos(180°-50°) = -cos(-50°) = -cos(50°)
sin(40°) = sin(90°-50°) = sin(90°)cos(50°) - cos(90°)sin(50°) = cos(50°)
tan(140°) = sin(140°)/cos(140°)
140° = 90°+50°