点(1,-1)到直线x-y+1=0的距离是(  ) A.12 B.32 C.22 D.322

问题描述:

点(1,-1)到直线x-y+1=0的距离是(  )
A.

1
2

B.
3
2

C.
2
2

D.
3
2
2

点(1,-1)到直线x-y+1=0的距离是:

|1−(−1)+1|
12+(−1)2
=
3
2
3
2
2

故选D.