alleryA square matrix $A$ is symmetric if
A$A'=-A$
B$AA'=I$
C$A'=A$
DEvery diagonal entry is zero
Answer & Solution
Correct answer: C. $A'=A$
By definition, a symmetric matrix satisfies $A'=A$, equivalently $a_{ij}=a_{ji}$ for all $i,j$.
**Option A is the condition for skew-symmetry, and option B is the condition for orthogonality.**
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