2分之a=4分之bb=2a2分之a=6分之cc=3aa方+b方+c方分之ab+bc+ca=(ax2a+2ax3a+3axa)/(a²+（2a）²+(3a)²)=(2a²+6a²+3a²)/(a²+4a²+9a²)=11a²/14a²=11/14...