(Solved):
Find an orthogonal matrix \( A \) where the first row is a multiple of \( (-1 ...
???????
Find an orthogonal matrix \( A \) where the first row is a multiple of \( (-1,3,0) \). \[ A=\left[\begin{array}{l} -1 / 2 \\ 3 / 2 \end{array}\right] \] Additional attempts available with new variants