A linear operator on R is called rigid if it does not change the lengths of vectors, and it is called angle preserving if it does not change the angle between nonzero vectors. a. Identify two different types of linear operators that are rigid. b. Identify two different types of linear operators that are angle preserving. c. Are there any linear operators on R2 that are rigid and not angle preserving? Angle preserving and not rigid? Justify your answer.