Write down the matrix for a rotation of \(90 ^ { \circ }\) anticlockwise about the origin.
Write down the matrix for a reflection in the line \(y = x\).
Find the matrix for the composite transformation of rotation of \(90 ^ { \circ }\) anticlockwise about the origin, followed by a reflection in the line \(y = x\).
What single transformation is equivalent to this composite transformation?