To find the new coordinates of point A (2, 4) after a 270-degree counterclockwise rotation, we can use the rotation transformation formula for a point (x, y) rotated by θ degrees around the origin (0, 0):
The new coordinates (x', y') after a rotation by θ degrees are given by:
\[ x' = x \cos(\theta) - y \sin(\theta) \]
\[ y' = x \sin(\theta) + y \cos(\theta) \]
For a 270-degree rotation (which is equivalent to a 90-degree clockwise rotation), we know:
- \(\cos(270^\circ) = 0\)
- \(\sin(270^\circ) = -1\)
Substituting these values into our formulas:
\[ x' = 2 \cdot 0 - 4 \cdot (-1) = 0 + 4 = 4 \]
\[ y' = 2 \cdot (-1) + 4 \cdot 0 = -2 + 0 = -2 \]
So after a 270-degree counterclockwise rotation, the new coordinates of point A (2, 4) will be (4, -2).
Thus, the answer is:
\[ \text{(4, -2)} \]