设B(x,y),则根据两点距离公式,有a=√[(x-1)²+y²]b=2c=√[(x+1)²+y²]因为a、b、c成等差数列所以√[(x-1)²+y²]+√[(x+1)²+y²]=2b=4化简,得x²/4+y²/3=1顶点B的轨迹...