sin210*=sin(180*+30*)=-sin30* = -1/2
cos210*=cos(180*+30*)=-cos30* = -sqrt(3)/2 (sqrt - квадратный корень)
tg210*=tg(180*+30*)=tg30*= 1/sqrt(3)
ctg210*=ctg(180*+30*)=ctg30*=sqrt(3)
