You can look into the problem : solving linear systems of equations by least squares method, as an example.

In this context, the related set of methodologies such as generalized inverse methods, biased regression methods such as Ridge regression and Principal components regression, sparse estimation methods such as LASSO regression, also deserves mention.

There is no mathematical subject as (coordinator geometry), that is Coordinate Geoemetry or Analytic Geometry which is invented & designed Rene Descartes. Also sometimes it is also called Cartesian Geometry in honor of R.Descartes.