1. Вычислите: a) sin(5π/4); б) tg(7π/6); в) cos(π/6) - ctg(π/4); г) tg(3π/4) * cos(3π/4) + ctg(-π/6) * sin(π/6); д) sin(510°) - sin(270°) * ctg(270°).

а) sin(5π/4) = sin(π + π/4) = -sin(π/4) = -√2/2 б) tg(7π/6) = tg(π + π/6) = tg(π/6) = √3/3 в) cos(π/6) - ctg(π/4) = √3/2 - 1 г) tg(3π/4) * cos(3π/4) + ctg(-π/6) * sin(π/6) = (-1) * (-√2/2) + (-√3) * (1/2) = √2/2 - √3/2 = (√2 - √3)/2 д) sin(510°) - sin(270°) * ctg(270°) = sin(360° + 150°) - (-1) * 0 = sin(150°) + 0 = sin(180° - 30°) = sin(30°) = 1/2