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
答
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.