已知点M（6,5,1）,N（3,2,2）,点P在xOy平面上,则｜PM｜+｜PN｜的最小值为

P(x,y,0)｜PM｜+｜PN｜=√[(x-6)^2+(y-5)^2+(0-1)^2]+√[(x-3)^2+(y-2)^2+(0-2)^2]≥2{[(x-6)^2+(y-5)^2+(0-1)^2]*[(x-3)^2+(y-2)^2+(0-2)^2]}^(1/4)等号当且仅当(x-6)^2+(y-5)^2+(0-1)^2=(x-3)^2+(y-2)^2+(0-2)^2成...