Calculate the center point between three pointsTh I have three positions, with an $X$ and $Y$ value and a value that indicates the distance to of each of the individual points (not in the same measurement). So to clarify my question:
I have three $XY$-positions and three values indicating the distance to the point (not in the same measurement). The lower the value is, the closer it is to the point.
For example: 
  Point $1(x:5,y:8,$strength$:43)$
  Point $2(x:22,y:23,$strength$:21)$
  Point $3(x:26,y:52,$strength$:132)$
I don't know if the values are actually usable/make sense as I made them up just now...
The main goal is to calculate a point in the "center" of the three points, though it can be outside
Picture to explain it further

Weighted ( by reciprocal strength $s$) average for each vertex
$$ \bar{ x} = \dfrac {x_1 s_1 + x_2 s_2 +x_3 s_3}{s_1+s_2+s_3} $$
$$ \bar{ y} = \dfrac {y_1 s_1 + y_2 s_2 +y_3 s_3}{s_1+s_2+s_3} .$$
where $$ s_i= \dfrac{1}{Strength_i} $$
