$33.2$ or $33.18…$

\( HD = 9.1 \text{ cm} \) (length of the base)
\( DC = 4 \text{ cm} \) (height)

Using the Pythagorean theorem
$
HC = \sqrt{HD^2 + DC^2}
$
$
HC = \sqrt{9.1^2 + 4^2}
$
$
= \sqrt{82.81 + 16}
$
$
= \sqrt{98.81}
$
$
HC \approx 9.94 \, \text{cm}
$
In triangle \( HGC \)
$
\tan(x) = \frac{ \text{height of the cuboid} }{ HC }
$
$
\tan(x) = \frac{6.5}{9.94}
$
$
\tan(x) \approx 0.654
$
$
x = \tan^{-1}(0.654)
$
$
x \approx 33.01^\circ
$