11.1 P = (0,0,0), (1,0,0), (1,1,0)

$$\frac{k}{m} \cot{ \delta}=\frac{1}{am}+\frac{r_0 m }{2}\frac{k^2}{m^2}$$ $P[0]=am$ , $P[1]=r_0m$

$$\begin{gather} \chi^2/d.o.f.=4.38186 \\ P[0]=-0.126547\pm (0.0017) \\ P[1]=-18.8546\pm (1.4) \\ \end{gather}$$ { $$\begin{gather} C=\begin{pmatrix} 3.05e-06& 0.351\\ 0.351& 1.89\\ \end{pmatrix} \end{gather}$$ }