Chapter 5.1, Problem 29EQ

In Exercises 29-32, use Exercise 28 to determine whether the given orthogonal matrix represents a rotation or a reflection. If it is a rotation, give the angle of rotation; if it is a reflection, give the line of reflection.

$\left[\begin{array}{l}\begin{array}{cc}-1/\sqrt{\sqrt{2}}& -1/\sqrt{2}\end{array}\\ \begin{array}{cc}1/\sqrt{2}& 1/\sqrt{2}\end{array}\end{array}\right]$