Solution
= Solution
An <antisymmetric matrix> satisfies $A^T=-A$. Each diagonal entry is therefore its own negative, so both diagonal entries vanish. Consequently
$$
\boxed{\operatorname{tr}A=0}.
$$
= Solution
An <antisymmetric matrix> satisfies $A^T=-A$. Each diagonal entry is therefore its own negative, so both diagonal entries vanish. Consequently
$$
\boxed{\operatorname{tr}A=0}.
$$