Question

найдите косинусы углов:
1) -17п4
2)17п6
3)-10п3
с решением плиз)

Answer 1

$Cos(-frac{17pi}{4})=Cos(4pi +frac{pi}{4})=Cosfrac{pi}{4}=frac{sqrt{2}}{2} \\Cosfrac{17pi}{6}=Cos(2pi+frac{5pi}{6})=Cosfrac{5pi}{6}=Cos(pi-frac{pi}{6})=-Cosfrac{pi}{6}=-frac{sqrt{3}}{2}\\Cos(-frac{10pi}{3} )=Cos(2pi+frac{4pi}{3} )=Cosfrac{4pi}{3}=Cos(pi +frac{pi}{3} )=-Cosfrac{pi}{3} =-frac{1}{2}$