设:正弦x,余弦y x^2+y^2=1 x/y=-2 x=-2y (-2y)^2+y^2=1 y=+(根号5)/5(舍) or y=-(根号5)/5 x=+2(根号5)/5 or y=-2(根号5)/5(舍) SinA=2(根号5)/5 CosA=-(根号5)/5
