Question

该岛形状为三角形,三边长a,b,c满足关系式3(a²+b²+c²)=(a+b+c)

Answer 1

3(a^2+b^2+c^2) =a^2+b^2+c^2 +2ac+2bc+2ab

2a^2+2b^2+2c^2=2ac+2bc+2ab

a^2 -2ab+b^2 +a^2-2ac+c^2 +b^2-2bc+c^2=0

(a-b)^2+(a-c)^2+(b-c)^2=0

得a=b=c 所以为等边三角形