Given:
The coordinates of the points A, B and C are (3,4), (4,3) and (2,1)
The points are rotated 90° about the origin.
We need to determine the coordinates of the point C'.
Coordinates of the point C':
The general rule to rotate the point 90° about the origin is given by
[tex](x, y) \Rightarrow(-y, x)[/tex]
Substituting the coordinates of the point C in the above formula, we get;
[tex](2, 1) \Rightarrow(-1, 2)[/tex]
Therefore, the coordinates of the point C' is (-1,2)