Cube has 6 flat faces and _________ straight edges.
Which of the following statements are true?
(i) All cubes are cuboids.
(ii) All cuboids are cubes.
(iii) A cube has 6 faces, 8 corners, and 12 edges.
(iv) A cube has 8 faces, 12 corners, and 6 edges.
If a polyhedron has 6 faces and 8 vertices, then it has ___ edges.