Eigenvalue Midpoint Trick

Process:

1. Find the midpoint $m=\frac{a+d}{2}$ which is the Matrix Trace/2
2. Find the product $\det (A)=ad-bc={\lambda }_1{\lambda }_2$ which is the Determinant
3. Then, ${\lambda }_1=m-\sqrt{m^2-p},{\lambda }_2=m+\sqrt{m^2-p}$

Example