若直线Z的倾斜角是连接p(3,-5),Q(0,-9)两点的直线的倾斜角的2倍,则直线l的斜率为____.
-(24/7)。设直线l的倾斜角为a,则直线PQ的倾斜角为2a,从而由tan2a=2tana/(1-tan2a),代人tana=[-9-(-5)]/(0-3)=4/3,得出tan2a=-(24/7).
若直线Z的倾斜角是连接p(3,-5),Q(0,-9)两点的直线的倾斜角的2倍,则直线l的斜率为____.
-(24/7)。设直线l的倾斜角为a,则直线PQ的倾斜角为2a,从而由tan2a=2tana/(1-tan2a),代人tana=[-9-(-5)]/(0-3)=4/3,得出tan2a=-(24/7).