A point is rotated about the origin. Its coordinates are P(−4,10) and P′(−10,−4). Determine the degree of rotation and direction by applying rotation mapping.(1 point)

Responses

90 degrees (counterclockwise)
90 degrees (counterclockwise)

−180 degrees (clockwise) or 180 degrees (counterclockwise)
negative 180 degrees (clockwise) or 180 degrees (counterclockwise)

270 degrees (counterclockwise)
270 degrees (counterclockwise)

−90 degrees (clockwise)

1 answer

To determine the degree of rotation and direction for the points \( P(-4, 10) \) and \( P'(-10, -4) \), we can use the rotation mapping of coordinates.

The general formulas for rotating a point \( (x, y) \) about the origin by \(\theta\) degrees counterclockwise are:

\[ (x', y') = (x \cos \theta - y \sin \theta, x \sin \theta + y \cos \theta) \]

We are given:

  • Initial point \( P(-4, 10) \)
  • Rotated point \( P'(-10, -4) \)

To find the angle \(\theta\), we can examine the transformations of the coordinates. Let's find out what happens to \( P \).

  1. Calculate the original distance of point P from the origin: \[ d_P = \sqrt{(-4)^2 + (10)^2} = \sqrt{16 + 100} = \sqrt{116} \approx 10.77 \]

  2. Calculate the distance of point P' from the origin: \[ d_{P'} = \sqrt{(-10)^2 + (-4)^2} = \sqrt{100 + 16} = \sqrt{116} \approx 10.77 \]

Both points \( P \) and \( P' \) are the same distance from the origin, confirming that this is a rotation around the origin.

  1. Next, to find an angle, we will consider the transformation of their coordinates.

    Original coordinates: \( P(-4, 10) \)

    After rotation: \[ P'(-10, -4) \]

    To determine the angle of rotation, look at the changes in their coordinates:

    • The x-coordinate changes from \(-4\) to \(-10\)
    • The y-coordinate changes from \(10\) to \(-4\)
  2. Geometric visualization:

    • Point \( P \) lies in the second quadrant (negative x, positive y).
    • Point \( P' \) lies in the third quadrant (negative x, negative y).

This indicates that the rotation has moved the point from the second quadrant to the third quadrant - typically reflecting a rotation of \( 180^{\circ} \).

  1. Calculating for the exact angle:

    Since the coordinates have shifted from:

    • \( x = -4 \) to \( x = -10 \) (which indicates a shift to negative on x)
    • \( y = 10 \) to \( y = -4 \) (which indicates a shift to negative on y)

This confirms that the rotation is:

\[ -180^\circ \text{ (clockwise) or } 180^\circ \text{ (counterclockwise)} \]

So the answer is: \[ \text{−180 degrees (clockwise) or 180 degrees (counterclockwise)} \]