第1个回答 2013-01-13
1、x²+y²-2x-4y+m=0
(x-1)²+(y-2)²=5-m
5-m>0
m<5
2、{(x-1)²+(y-2)²=5-m,x+2y-4=0
解得:{x=-1+√(9-2m),y=[5+√(9-2m)]/2;x=-1-√(9-2m),y=[5-√(9-2m)]/2
∵OM⊥ON,OM=ON
∴MN²=2OM²
{[5+√(9-2m)]/2-[5-√(9-2m)]/2}²+{-1+√(9-2m)-[-1-√(9-2m)]}²=2(5-m)
9-2m+4(9-2m)=2(5-m)
m=35/8