Determine the effect of the matrix M=(01−10)M = \begin{pmatrix} 0 & 1 \\ -1 & 0 \end{pmatrix}M=(0−110) on a vector in the plane.
Rotation 90∘90^\circ90∘ CCW
Rotation 90∘90^\circ90∘ CW
Reflection across y=xy=xy=x
Reflection across y=−xy=-xy=−x