Question

Вычислите: а) sin 9п/4= б) cos ( -4п/3)= в) tg (-7п/6) = г) ctg 5п/4

Answer 1

$sin (frac{9 pi}{4})=sin (2 pi +frac{ pi}{4})=sin (frac{pi}{4})=frac{sqrt{2}}{2} \ \ cos (-frac{4 pi}{3})=cos (frac{4pi}{3})=cos (pi + frac{pi}{3})=-cos (frac{pi}{3})=- frac{1}{2} \ \ tg(-frac{7pi}{6})=-tg(frac{7pi}{6})= - tg (pi + frac{pi}{6})=-tg (frac{pi}{6})=-frac{sqrt{3}}{3} \ \ ctg(frac{5 pi}{4})=ctg (pi+frac{pi}{4})=ctg (frac{pi}{4})=1$

Answer 2

1)sin9π/4=sin(2π+π/4)=sinπ/4=√2/2
2)cos(-4π/3)=cos(4π/3)=cos(π+π/3)=-cosπ/3=-1/2
3)tg(-7π/6)=-tg(7π/6)=-tg(π+π/6)=-tgπ/6=-√3/3
4)ctg5π/4=ctg(π+π/4)=ctgπ/4=1