Let \(T:\mathbb R^3\to\mathbb R^3\) be a rotation about the axis determined by \((1,0,-1)\) through an angle of \(30^\circ\); either orientation may be used.
Find the matrix representation \(A\in M_3(\mathbb R)\) of \(T\) in the standard basis. You need not multiply out matrices, but you must evaluate inverses.
Find all eigenvalues of \(A\) in \(M_3(\mathbb R)\).
Find all eigenvalues of \(A\) when regarded as an element of \(M_3(\mathbb C)\).