圆心F(-3,0),半径 =1
显然圆完全在直线l左侧
设所求圆的半径为r,圆心M(x,y),r = 2 - x
MF² = (1 + r)² = (3 - x)²
另外MF² = (x + 3)² + (y - 0)² = (x + 3)² + y²
于是:(3 - x)² = (x + 3)² + y²
y² = -12x
此为心M的轨迹方程.
圆心F(-3,0),半径 =1
显然圆完全在直线l左侧
设所求圆的半径为r,圆心M(x,y),r = 2 - x
MF² = (1 + r)² = (3 - x)²
另外MF² = (x + 3)² + (y - 0)² = (x + 3)² + y²
于是:(3 - x)² = (x + 3)² + y²
y² = -12x
此为心M的轨迹方程.