Find the angel between any two diagonals of a cube.

Explanation

To find the angle between any two diagonals of a cube, we can follow these steps:

### Step 1: Define the cube and its vertices
Let’s consider a cube with vertices defined in a 3D coordinate system. We can place one vertex at the origin (0, 0, 0) and the other vertices at the following coordinates, assuming the side length of the cube is 'a':
- A (0, 0, 0)
- B (a, 0, 0)
- C (a, a, 0)
- D (0, a, 0)
...