Answer
See below
Work Step by Step
Assume $=a_{11}b_{11}+a_{12}b_{12}+a_{21}b_{21}+a_{22}b_{22}$
Obtain:
$=3.1+2.1+(-2).(-2)+4.1=13\\
||A||=\sqrt =\sqrt 3.3+2.2+(-2).(-2)+4.4=\sqrt 33\\
||B||=\sqrt =\sqrt 1.1+1.1+(-2).(-2)+1.1=\sqrt 7$
The angle between matrices $A$ and $B$:
$$\cos \theta=\frac{}{{{A}}.||B||}=\frac{13}{\sqrt 33.\sqrt 7}=\frac{13}{\sqrt 231}\\
\theta =\arccos\frac{13}{\sqrt 231}$$
