When rotating points and shapes on a coordinate plane, you can use these simple methods:
90 degree rotation clockwise: convert (x, y) to (y, -x).
Example: (2, -4) --> (4, 2)
180 degree rotation clockwise: convert (x, y) to (-x, -y).
Example: (2, 4) --> (-2, -4).
270 degree rotation clockwise: convert (x, y) to (-y, x).
Example: (4, 2) --> (-2, 4)
360 degree rotation: This changes nothing. This basically means that the figure spins in a full circle only to return to its previous position.
Notes:
-Don't be spooked whenever you see a question that says to rotate an object 90 degrees counterclockwise. This is the exact same thing as a 270 degree rotation clockwise.
Example: (4, 2) rotated 270 degrees clockwise = (2, -4). (4, 2) rotated 90 degrees counterclockwise = (2, -4).
