题目内容
A.x-y-3=0 B.x+2y=0 C.x+y-1=0 D.2x-y-5=0
A
解析:消去参数得圆的普通方程,利用垂直关系,求得直线方程x-y-3=0.应选A.
若P(2,-1)为圆O'的弦的中点,则该弦所在直线l的方程是( )
A.x-y-3=0
B.x+2y=0
C.x+y-1=0
D.2x-y-5=0
A.x-y-3=0 B.2x+y-3=0 C.x+y-1=0 D.2x-y-5=0
B.2x+y-3=0