PHY3707
ASSIGNMENT 1
Solid State Physics
FULL SOLUTIONS
COMPLETE SOLUTIONS
MEMORANDUM
UNISA 2026
Page 1 of 7
, SOLUTION
Consider a cube of side length 𝑎. Place the cube with vertices at (0, 0, 0) and (𝑎, 𝑎, 𝑎).
The four body diagonals of the cube run from one vertex to the opposite vertex.
However, the tetrahedral angle is the angle between two diagonals that share a
common vertex.
Page 2 of 7
ASSIGNMENT 1
Solid State Physics
FULL SOLUTIONS
COMPLETE SOLUTIONS
MEMORANDUM
UNISA 2026
Page 1 of 7
, SOLUTION
Consider a cube of side length 𝑎. Place the cube with vertices at (0, 0, 0) and (𝑎, 𝑎, 𝑎).
The four body diagonals of the cube run from one vertex to the opposite vertex.
However, the tetrahedral angle is the angle between two diagonals that share a
common vertex.
Page 2 of 7