3(a的2次方+b的二次方+c的二次方)=(a+b+c)的2次方,3a^2+3b^2+3c^2=a^2+b^2+c62+2ab+2bc+2ca2a^2+2b^2+2c^2-2ab-2bc-2ca=0(a^2-2ab+b^2)+(b^2-2bc+c^2)+(c^2-2ca+a^2)=0(a-b)^2+(b-c)^2+(c-a^2)=0a=b b=c c=aa=b=c等边三角形
答案是等边三角形,a=b=c经推导得出(a-b)2+(a-c)2+(b-c)2=0所以a=b=c