если sinα=√2/2, α∈[90°;270°] cosα=-√2/2
1/2 + √2*(-√2/2)=-1/2
2) cosα = √2/2, α∈[180°;360] sinα=-√2/2
√2/10*(-√2/2) + 2=-1/10+2=1,9
если sinα=√2/2, α∈[90°;270°] cosα=-√2/2
1/2 + √2*(-√2/2)=-1/2
2) cosα = √2/2, α∈[180°;360] sinα=-√2/2
√2/10*(-√2/2) + 2=-1/10+2=1,9