To find the new coordinates \( C' \) after a \( -90^\circ \) (clockwise) rotation about the origin, you can use the rotation transformation formulas.
For a point \( (x, y) \):
\[ (x', y') = (y, -x) \]
- Start with the coordinates of point \( C(x, y) \).
- Apply the transformation:
\[ C' = (y, -x) \]
If you provide the original coordinates of point \( C \), I can help you calculate the coordinates of \( C' \).