1. The problem statement, all variables and given/known data Hi I have a coordinate system (x', y') and a vector v'=(1, 0) here. There is a different coordinate system (x, y), which is rotated about the y-axis relative to (x', y') by an angle Ω. I am trying to express v' in the system (x, y). At first what I tried to do was to rotate v' by an angle Ω around the y-axis by a rotation matrix, but then it occurred to me that this only rotates the vector, it does not express it in the system (x, y). Can I get a hint to how to achieve this? Thanks in advance.