The First Principal Direction

$\dfrac{1}{\sqrt{5}}\begin{bmatrix} 2 \\ 1 \end{bmatrix} \approx \begin{bmatrix} 0.894 \\ 0.447 \end{bmatrix}$

$\dfrac{1}{\sqrt{5}}\begin{bmatrix} 1 \\ -2 \end{bmatrix} \approx \begin{bmatrix} 0.447 \\ -0.894 \end{bmatrix}$

$\begin{bmatrix} 2 \\ 1 \end{bmatrix}$

$\dfrac{1}{\sqrt{5}}\begin{bmatrix} 1 \\ 2 \end{bmatrix} \approx \begin{bmatrix} 0.447 \\ 0.894 \end{bmatrix}$