Question

If $A=\frac{1}{3}\left[\begin{array}{ccc}1& 2& 2\\ 2& 1& -2\\ a& 2& b\end{array}\right]$ is an orthogonal matrix, then

• A. $a=-2$
• B. $a=2,b=1$
• C. $b=-1$
• D. $b=1$

Answer 1

Answer: (A), (C)

The correct options are
A $a=-2$
C $b=-1$