10 класс: 1)2sin x = корень 2; 2)cos x = корень 3/2; 3)cos x = 4/5; 4)ctgx = 1/корень 3

1) 2sinx=√2
sinx=√2/2
x=Π/4+2ΠK; k€Z

2)cosx=√3/2
x= Π/6+2ΠK; k€Z

3)cosx=4/5
cosx=0.8
x=(0.8*180/Π)
x=144/Π

4)ctgx=1/√3
ctg=1/tg
tg=√3
x=arctag√3+2ΠK; k€Z
x= Π/3+2ΠK; k€Z