Show that the elements along the main diagonal of a skew symmetric matrix are all zero.
For a skew symmetric matrix A
AT + A = 0
AT = -A---------eq.1
Diagonal elements of A = Diagonal elements of AT ------eq.2
Now from eq.1 and eq.2
Diaganol elements of A and Diagonal elements of AT should be equal as well as of opposite signs
This is possible only when all diagonal elements are 0