(2011•安徽模拟)若点P(1,1)为圆(x-3)2+y2=9的弦MN的中点,则弦MN所在直线方程为( ) A.2x+y-3=0 B.x-2y+1=0 C.x+2y-3=0 D.2x-y-1=0
问题描述:
(2011•安徽模拟)若点P(1,1)为圆(x-3)2+y2=9的弦MN的中点,则弦MN所在直线方程为( )
A. 2x+y-3=0
B. x-2y+1=0
C. x+2y-3=0
D. 2x-y-1=0
答
圆心C(3,0),kpc=−
,kMN=2,∴MN方程为y-1=2(x-1),即2x-y-1=0,1 2
故选D.