Tg0°-2ctg90°-sin0°-3cos90°=

1) cos720+tg 30 ctg 210+sin 120 = сos2*360° + tg30°ctg (180° + 30°) +

+ sin (90° + 30) ° = 1 + 1/√3*ctg30° + sin30° = 1 + (1/√3) * (√3) + 1/2 = 1 + 1 + 1/2 = 2 (1/2)

tg0 ° - 2ctg90° - sin0° - 3cos90° = 0 - 2*0 - 0 - 3*0 = 0