Explore how coordinates change as you rotate a triangle about the origin.

1. Make a prediction as to how the coordinates for each point on the triangle will change as you rotate it about the origin in 90° increments.
2. Quickly move the slider from 0° degrees to 360°. Look at the traced triangle and points. How does it compare to your original prediction?
3. Slowly move the slider to 90°, 180°, and 270° and record the new coordinates for each point.
4. For each rotation (90°, 180°, and 270°) how does it change from the original triangle? Write a general rule in coordinate form for each rotation.
5. Extension: How can we relate this to matrices? Write a matrix to represent the change that could be multiplied by the matrix of coordinates.