Math Problem Statement

given a point is (x,y) what is the new point when the point is rotated counterclockwise about the origin 270 degrees

Solution

When a point (x,y)(x, y) is rotated counterclockwise about the origin by 270 degrees, the new coordinates can be calculated using a rotation matrix.

The general rotation formula for counterclockwise rotation by θ\theta degrees is:

[xy]=[cosθsinθsinθcosθ][xy]\begin{bmatrix} x' \\ y' \end{bmatrix} = \begin{bmatrix} \cos \theta & -\sin \theta \\ \sin \theta & \cos \theta \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix}

For a 270° rotation, we use the values:

cos270=0,sin270=1\cos 270^\circ = 0, \quad \sin 270^\circ = -1

Thus, the rotation matrix for 270° counterclockwise becomes:

[0110]\begin{bmatrix} 0 & 1 \\ -1 & 0 \end{bmatrix}

Multiplying this matrix by the point (x,y)(x, y):

[xy]=[0110][xy]\begin{bmatrix} x' \\ y' \end{bmatrix} = \begin{bmatrix} 0 & 1 \\ -1 & 0 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix}

This gives:

x=y,y=xx' = y, \quad y' = -x

Thus, after rotating the point (x,y)(x, y) by 270 degrees counterclockwise about the origin, the new point will be:

(x,y)=(y,x)(x', y') = (y, -x)

Example:

If the original point is (3,4)(3, 4), after a 270° counterclockwise rotation, the new point will be:

(4,3)(4, -3)

Would you like more details or a specific example?


Here are 5 related questions for further learning:

  1. What is the result of rotating the point (2, 3) by 90° counterclockwise about the origin?
  2. How do rotation transformations behave for negative angles, such as -90° or -270°?
  3. What is the formula for rotating a point around another point, not the origin?
  4. How do the coordinates change for a 180° counterclockwise rotation?
  5. Can this method of rotation be applied to 3D coordinates, and if so, how?

Tip: To visualize rotations, graph the original and rotated points on a coordinate plane to better understand the transformation.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Rotation Transformations
Linear Algebra

Formulas

Rotation Matrix: [ [cosθ, -sinθ], [sinθ, cosθ] ]
For 270° counterclockwise: x' = y, y' = -x

Theorems

Rotation Transformation Theorem

Suitable Grade Level

Grades 9-12