1. Take a piece of paper.
2. Draw an x-y coordinate axes any way you like.
3. Now fix that paper on your desk or on the floor so that it won't move for now.
4. Pick a particular direction to draw. This could be the direction where the window is, or a door, or a particular home decor piece.
5. Draw a straight line on your graph from the origin, along the direction of that object that you chose in #4.
6. Now rotate your graph paper by some angle.
7. While the line that you drew indicating the direction of that object you chose in #4 also rotates with your axes, it NO LONGER REPRESENTS THAT DIRECTION
. The direction to that object hasn't changed! Your graph paper and the orientation of your axes have. That line pointing towards your object in #4 needs to be redrawn!
8. If you find this confusing, put a compass on the origin of your axes, and rotate your graph paper. The needle pointing north should not care that you've just rotated your axes. If it does, you may be sitting in the middle of the Bermuda Triangle.