4.2 sin 225º - cos 495° - tg 330° - ctg 600°

sin(225°) = sin(180°+45°) = -sin(45°) = -√2/2; cos(495°) = cos(495°-360°) = cos(135°) = cos(180°-45°) = -cos(45°) = -√2/2; tg(330°) = tg(360°-30°) = -tg(30°) = -1/√3; ctg(600°) = ctg(600°-360°) = ctg(240°) = ctg(180°+60°) = ctg(60°) = 1/√3. -√2/2 - (-√2/2) - (-1/√3) - 1/√3 = -√2/2 + √2/2 + 1/√3 - 1/√3 = 0