Show that the elements on the main diagonal of a skew-symmetric matrix are all zero.

Explanation

To show that the elements on the main diagonal of a skew-symmetric matrix are all zero, we will follow these steps:

### Step 1: Definition of a Skew-Symmetric Matrix
A matrix \( A \) is called skew-symmetric if it satisfies the condition:
\[ A^T = -A \]
where \( A^T \) is the transpose of matrix \( A \).
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