1. The problem statement, all variables and given/known data Write the matrix of a rotation tensor corresponding to the rotation by angle θ about an axis aligned with e1+e2 2. Relevant equations I know that the matrix for a rotation tensor about e3 is; cosθ -sinθ 0 sinθ cosθ 0 0 0 0 3. The attempt at a solution I assume that the rotation would be changing only on the e3 axis because the axis are aligned with e1+e2, right? So the matrix will be all zero with the R33 component being some complicated rotated value?