cos(t) = син(t + π/2) = сin(π/2 - t) = сos(t) и ctg(t) = 1 / tg(t) = 1 / (сin(t) / сos(t)) = сos(t) / сin(t) = cotg(t)

cos(t) = 3/5, tg(t) = sin(t) / cos(t) = 4/3, ctg(t) = 3/4