几道选择题求助,大家快来,明早要交~
1.与一对平行直线5x-2y-6=0,10x-4y+3=0等距离的点的轨迹方程是( ). A.20x-8y-9=0 B.10x-4y-5=0 C.5x-2y-3=0 D.15x-6y-11=0 2.直线:根号3*x+y-2*根号3=0,截圆x^2+y^2=4得出劣弧所对的圆心角为( ). A.派/6 B.派/4 C.派/3 D.派/2 3.光线由点P(2,3)射到直线x+y=-1上,反射后过点Q(1,1),则反射光线方程为( ). A.-x+y=0 B.4x-5y-31=0 C.4x-5y+1=0 D.4x-5y+16=0
1、A 由平行线间距离设直线L:5x-2y+c=0 有|c+6|=|c-3/2| L在两平行线间,所以-6<c<3/2 去绝对值得,C=9/4 选A 2、A 直线倾斜角120度,补角60度,截圆的弦与圆心组成等腰三角形,底角60度,顶角30度即为圆心角 3、C P点关于直线对称点A(-4,-3)反射光线过A及Q,由两点式写方程
A A C
答:1.You are not stupid,( ) you were slow in study,you shouldn't have given it up. ...详情>>
答:158###25000###198###458详情>>