# Solving a set of equations

I have a set of n equations of the form of $Z_i((a-x_i)^2 + (b-y_i)^2 + c^2)$, i varies from 1 to n and $Z_i$, $x_i$, $y_i$ are knowns and $a,b,c$ are unknown. They are all equal to each other meaning $Z_i((a-x_i)^2 + (b-y_i)^2 + c^2) = Z_j((a-x_j)^2 + (b-y_j)^2 + c^2) \forall i, j$

Can someone help me to solve the equation for best fit a,b,c ?

Thanks

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