Найдите значение: а) sin 2,5pi; б) cos (-9pi/2); в) tg 13pi/6; г) sin (-9pi/2); д) ctg 13pi/3; е) tg (-17pi/4)

А) Sin2,5π = Sin(2π + 0,5π) = Sin0,5π = 1
б)Cos(-9π /2) = Cos9π/2 = Cos(4π + 0,5π) = Cos0,5π = 0
в) tg13π/6 = tg(2π + π/6) = tg π/6 = √3/3
г)Sin(-9π/2) = -Sin9π/2 = - Sin(4π + 0,5π) = -Sin0,5π = -1
д) Ctg13π/3 = Ctg(4π + π/3) = Ctgπ/3 = √3/3
e) tg(-17π/4) = - tg17π/4 = - tg( 4π + π/4) = -tg π/4 = -1