把sinα=(k-2)/(k+2),cosα=k/(k+2),代入sin²α+cos²α=1得(k-2)²/(k+2)²+k²/(k+2)²=1(k-2)²+k²=(k+2)²整理得：k²-8k=0k(k-8)=0解得k1=0,k2=8①当k1=0时,sinα=-...