To determine the new coordinates of point Y after a -270-degree rotation about the origin, we can use the rotation transformation formulas for a point \((x, y)\).
The rotation formulas for a \(-\theta\) degree rotation about the origin are:
\[ x' = x \cos(-\theta) - y \sin(-\theta) \] \[ y' = x \sin(-\theta) + y \cos(-\theta) \]
For a \(-270\) degree rotation, it is equivalent to a \(90\) degree rotation (since \(-270\) + \(360\) = \(90\)). The cosine and sine values for \(90\) degrees are:
- \(\cos(90^\circ) = 0\)
- \(\sin(90^\circ) = 1\)
Thus, the transformation equations for a \(90\) degree rotation around the origin modify to:
\[ x' = 0 \cdot x - 1 \cdot y = -y \] \[ y' = 1 \cdot x + 0 \cdot y = x \]
Now we apply this to point Y, which has coordinates \((-9, -1)\):
-
Calculate \(x'\): \[ x' = -(-1) = 1 \]
-
Calculate \(y'\): \[ y' = -9 \]
Thus, the new coordinates \(Y' = (1, -9)\).
Therefore, the coordinates of the image of \(Y\) after a \(-270^\circ\) rotation about the origin are:
\[ Y' \left( 1, -9 \right) \]