Question

If a matrix A is symmetric as well as skew symmetric, then

• A. A is a diagonal matrix
• B. A is a null matrix
• C. A is a unit matrix
• D. A is a triangular matrix

Answer 1

Answer: (B)

Since A is symmetric $\therefore$ A' = A
Since A is skew symmetric $\therefore$ A' = - A .
$\therefore$ A = - A $\Rightarrow$ 2A = O $\Rightarrow$ A = O.