If
\[
A = \begin{bmatrix} 0 & c & -b \\ -c & 0 & a \\ b & -a & 0 \end{bmatrix}, \quad B = \begin{bmatrix} a^2 & ab & ac \\ ab & b^2 & bc \\ ac & bc & c^2 \end{bmatrix},
\]
then \( AB \) is equal to:
Show Hint
Matrix multiplication can result in the zero matrix when matrices are orthogonal or in certain symmetric forms.
When multiplying matrices \( A \) and \( B \), the result is the zero matrix \( O \), indicating that the matrices are orthogonal.
Final Answer:
\[
\boxed{O}
\]