点M(1,3),直线L:x=1-2t/√5,y=3+t/√5.(t为参数)与圆x=1+cosΘ,y=5+sinΘ相交与P1,P2两点.求lMP1l-lMP2l
问题描述:
点M(1,3),直线L:x=1-2t/√5,y=3+t/√5.(t为参数)与圆x=1+cosΘ,y=5+sinΘ相交与P1,P2两点.求lMP1l-lMP2l
答
x=1-2t/√5,y=3+t/√5
x+2y-7=0,所以M(1,3)在直线L上
x=1+cosΘ,y=5+sinΘ
(x-1)^2+(y-5)^2=1,所以M(1,3)在圆外,圆的直径为2
所以lMP1l-lMP2l=2或-2