Question

If $A$ is orthogonal matrix, then $A^{-1}$ equals

• A. $A$
• B. $A^{\prime }$
• C. $A^2$
• D. None of these

Answer 1

The correct option is B $A^{\prime }$

$A$ is an orthogonal matrix

i.e $A{A}^T=I$

$\Rightarrow A^{-1}A{A}^T=A^{-1}I$

$\therefore A^{-1}=A^T$