Solution, in Maxima, of the least-squares problem described at 
http://www.inference.phy.cam.ac.uk/teaching/comput/
"A straight line y = mx is to be fitted (by least squares) to a data set that happens to lie uniformly on a circle of radius 1 centred at (1,1)." 
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(C1)  x(t) := 1+cos(t);

(D1)                          x(t) := 1 + COS(t)
(C2)  y(t) := 1+sin(t);

(D2)                          y(t) := 1 + SIN(t)
(C3)  integrate( (y(t)-m*x(t))**2 , t,0,2*%pi ) / (2*%pi)   ;

                                 2
                          3 %PI m  - 4 %PI m + 3 %PI
(D3)                      --------------------------
                                    2 %PI
(C4)  diff( % , m ) ;

                                6 %PI m - 4 %PI
(D4)                            ---------------
                                     2 %PI
(C5)  solve( % ) ;

                                         2
(D5)                                [m = -]
                                         3