当y＞0时,终边落在第二象限,sinα＞0,∠α为钝角,且sinα=sin(180°-α)sin(180°-α)=y/√(3+y²)=√3y/4,解得y=√21/3,角是第二象限角,sinα=√3y/4=√3/4*√21/3=√7/4 cosα=-√(1-sin²α)=-3/4tanα=s...