вычислите cos(t-2П),ctg(-t),sin(4П-t),если tgt= -√5/2, П/2

спасибо, спасла

сos(t - 2π) = cos(2π - t) = costcos^2t = 1/(tg^2t + 1)cos^2t = 1/(5/4 + 1)cos^2t = 4/9cost = -(2/3)cost = (2/3)ctg(-1) = - ctgt,  tgt = -√5/2, tgt*ctgt = 1,ctgt = 1/tgt,  ctgt = 1/(-√5/2)sin(4π - t) = sint sint = √(1 - cos^2x) = √[1 - (2/3)^2] = √5/3