a²-2bc=b²-2aca²-2bc-b²+2ac=0a²+2ac+c²-b²-2bc-c² +c²-c²-=0(a+c)²- (b²+2bc+c²)=0(a+b)²-(b+c)²=0(a+b)²=(b+c)²所以a=b所...