Math Problem Statement

Triangle FGH is shown below and has vertices F(2, -1), G(5, -3), and H(1, -4). After a 180° clockwise rotation of △FGH about the point (1, -2), what are the new coordinates of △F'G'H'?

Solution

To solve this problem, we need to determine the new coordinates of the vertices FF, GG, and HH after a 180° clockwise rotation around the point (1,2)(1, -2).

Steps to Perform a 180° Rotation

For a 180° rotation about a specific point (a,b)(a, b), the rotation formula for any point (x,y)(x, y) is: (x,y)=(2ax,2by)(x', y') = (2a - x, 2b - y) This formula shifts the coordinates of each point to its rotated location.

Given Points and Rotation Point

  • Rotation Point (a,b)=(1,2)(a, b) = (1, -2)
  • Points to rotate:
    • F(2,1)F(2, -1)
    • G(5,3)G(5, -3)
    • H(1,4)H(1, -4)

Applying the Formula

  1. For F(2,1)F(2, -1): F=(212,22(1))F' = (2 \cdot 1 - 2, 2 \cdot -2 - (-1)) F=(22,4+1)=(0,3)F' = (2 - 2, -4 + 1) = (0, -3)

  2. For G(5,3)G(5, -3): G=(215,22(3))G' = (2 \cdot 1 - 5, 2 \cdot -2 - (-3)) G=(25,4+3)=(3,1)G' = (2 - 5, -4 + 3) = (-3, -1)

  3. For H(1,4)H(1, -4): H=(211,22(4))H' = (2 \cdot 1 - 1, 2 \cdot -2 - (-4)) H=(21,4+4)=(1,0)H' = (2 - 1, -4 + 4) = (1, 0)

Result

After a 180° clockwise rotation about the point (1,2)(1, -2), the vertices of the triangle become:

  • F=(0,3)F' = (0, -3)
  • G=(3,1)G' = (-3, -1)
  • H=(1,0)H' = (1, 0)

Would you like further explanation on any part of this solution, or have additional questions?


Here are five related questions to expand on this concept:

  1. How would the coordinates change if the rotation was 90° instead of 180°?
  2. What would the coordinates be if we rotated the triangle around the origin instead of (1,2)(1, -2)?
  3. Can you apply this rotation formula to other shapes, like rectangles or polygons?
  4. How can you verify the results of a rotation mathematically?
  5. What is the geometric significance of rotating by 180°?

Tip: When rotating points around a specific center, remember that a 180° rotation simply reflects each point through that center, making it an easy transformation to visualize.

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Math Problem Analysis

Mathematical Concepts

Coordinate Geometry
Rotations
Transformations

Formulas

(x', y') = (2a - x, 2b - y)

Theorems

Properties of 180° rotation about a point

Suitable Grade Level

Grades 9-11