1. Вычислите: a) sin (-2π/3); б) tg (7π/6); в) cos(π/2) - ctg(5π/4); г) ctg(π/3) tg(-π/3) - cos(-π) sin(π); д) tg 720° + sin 540° - ctg 135°.

a) \( sinleft(-rac{2pi}{3} ight) = -sinleft(rac{2pi}{3} ight) = -sinleft(pi - rac{pi}{3} ight) = -sinleft(rac{pi}{3} ight) = -rac{sqrt{3}}{2} \) б) \( anleft(rac{7pi}{6} ight) = anleft(pi + rac{pi}{6} ight) = anleft(rac{pi}{6} ight) = rac{sqrt{3}}{3} \) в) \( cosleft(rac{pi}{2} ight) - cotleft(rac{5pi}{4} ight) = 0 - cotleft(pi + rac{pi}{4} ight) = - cotleft(rac{pi}{4} ight) = -1 \) г) \( cotleft(rac{pi}{3} ight) anleft(-rac{pi}{3} ight) - cos(-pi) sin(pi) = cotleft(rac{pi}{3} ight) left(- anleft(rac{pi}{3} ight) ight) - (-1) cdot 0 = -cotleft(rac{pi}{3} ight) anleft(rac{pi}{3} ight) = -rac{sqrt{3}}{3} cdot sqrt{3} = -1 \) д) \( an(720^circ) + sin(540^circ) - cot(135^circ) = an(2 cdot 360^circ) + sin(360^circ + 180^circ) - cot(90^circ + 45^circ) = 0 + sin(180^circ) - (- an(45^circ)) = 0 + 0 + 1 = 1 \)