O(0,0),A(c,0) 设M(x,y) MO^2=x^2+y^2 MA^2=(x-c)^2+y^2 MO^2-MA^2=c x^2+y^2-[(x-c)^2+y^2]=c 与点O(0,0)与A(c,0)的距离的平方差为常熟c的点的轨迹方程：x=(1+c)/2 证：M[(1+c)/2 ,y] MO^2=(1+c)^2/4+y^2 MA^2=[(1+...