4.1 sin 150° + cos 120° + tg 135° + ctg 225°

sin(150°) = sin(180°-30°) = sin(30°) = 1/2; cos(120°) = cos(180°-60°) = -cos(60°) = -1/2; tg(135°) = tg(180°-45°) = -tg(45°) = -1; ctg(225°) = ctg(180°+45°) = ctg(45°) = 1. 1/2 -1/2 -1 + 1 = 0