用ma,mb,mc分别表示BC,CA,AB边上中线的长.ma=(1/2)√(2b^2+2c^2-a^2)mb=(1/2)√(2a^2+2c^2-b^2)mc=(1/2)√(2a^2+2b^2-c^2)于是4ma^2=2b^2+2c^2-a^2.(1)4mb^2=2a^2+2c^2-b^2.(2)4mc^2=2a^2+2b^2-c^2.(3)用(1)(2)(3)联...