Prove that the tetrahedron with vertices at the points `O(0,0,0),\ A(0,1,1), B(1,0,1)a n d\ C(1,1,0)` is a regular one.

Explanation

To prove that the tetrahedron with vertices at the points \( O(0,0,0), A(0,1,1), B(1,0,1), C(1,1,0) \) is a regular tetrahedron, we need to show that all the edges of the tetrahedron are of equal length.

### Step 1: Identify the vertices
The vertices of the tetrahedron are:
- \( O(0,0,0) \)
- \( A(0,1,1) \)
- \( B(1,0,1) \)
- \( C(1,1,0) \)
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