Area bounded by $y=f^{-1}\left(x\right)$ and tangent and normal drawn to it at the points with abscissa $\pi \text{and} 2\pi$, where $f\left(x\right)=\sin x-x$ is:

Statement I: The area bounded by the curves $y=x^2-3$ and $y=kx+2$, is least if  $k=0.$

Statement II: The area bounded by the curves $y=x^2-3$ and $y=kx+2$ is $\sqrt{k^2+20}.$