Solution: Let the coordinate of the point be P(x, y),

What is the square of the distance from point p to o? x^2+y^2

The square of the distance from point p to a is (x-c) 2+y 2.

x^2+y^2-(x-c)^2-y^2=c

Get 2cx = c+c 2.

Then the trajectory is x=( 1+c)/2.

2.

Establish a rectangular coordinate system with the midpoint of two fixed points as the origin.

The coordinates of the two fixed points are (-3,0) (3,0) respectively.

Let the coordinates of point M be (x, y).

Yes: (x+3) 2+y 2+(x-3) 2+y 2 = 26.

x^2+y^2=4

M-point trajectory is round?

3.

I just drew a circle, okay? And the main conditions may be embarrassed to come.