The size of the angle is 48.2 degrees to 3 significant figures
The trigonometric functions are mathematical functions that establish relationships between an angle within a right-angled triangle and the ratios of its side lengths.
The trigonometric functions are defined as follows:

In the context of a cuboid, consider Triangle BHG as a right triangle, where:
- BG = 24 cm (adjacent side)
- BH = 36 cm (opposite side)
Let's represent the angle HBG as x:

Solving for
, which corresponds to approximately
x = cos ⁻(0.667)
= 48.2 degrees