Calculating coordinates from several other coordinates

Question

I use trilateration to determine the coordinates of a mobile anchor with other fixed anchors. (2D)
Here is the algorithm I use and it works very well.

The problem is that I have several possible coordinates, here is an example :

P (red) is the original point; P_x (blue) are the calculated point.
Representation of the coordinates calculated by trilateration

I would like to find a mathematical algorithm that uses all the points P_x to calculate an approximate point of P that we can call P_appr.
This algorithm must remove the points that are too far away.
In the previous example, they are all good, but we can imagine some very distant point such as P₁₀, P₁₁ amd P₁₂ which should be ignored in this example.

Representation of calculated coordinates, some of which must be ignored

I have no idea how to calculate P_appr with all the P_x coordinates.
Does somebody have an idea ?

I have no idea how to calculate P_appr with all the P_x coordinates.
Does somebody have an idea ?