Consider the following statements regarding 2D transforms in computer graphics: 1 0 [ ] 2 × 2

S1 : is a matrix that reflects 0 −1 2D X (mirrors) only point about the -axis. 2 × 2 2D

S2 : A matrix which mirrors any point X about the -axis, is a rotation matrix. What can you say about the statements S1 and S2?

1. ABoth S1 and S2 are true
2. BOnly S1 is true
3. COnly S2 is true
4. DBoth S1 and S2 are false

Pick an option to check yourself, or open the answer below.

Show answer & explanation

Correct answer: B. Only S1 is true

Explanation

[1 0; 0 −1] reflects about the x-axis. A reflection has determinant −1, while every rotation has +1, so no reflection matrix is a rotation.