dentify a sequence of rigid transformations that would map ABCD → A" B" C'" D". Give your answer in the form of a composition transformation mapping.

& point)
• (х, у) → (-х, у - 4)
O (2.3) - (-2- 4,3)
0 (2-3)→(2-3+4)
0(2:3) → (2,-9-4)

1 answer

To determine the sequence of rigid transformations that maps quadrilateral ABCD to A" B" C'" D", we need to analyze the provided transformations.

The transformation you've mentioned is:

  • \((x, y) \to (-x, y - 4)\)

This transformation can be broken down into two separate transformations:

  1. Reflection across the y-axis: This changes \((x, y)\) to \((-x, y)\).
  2. Translation downward: This changes \((-x, y)\) to \((-x, y - 4)\).

Let's denote the points of quadrilateral ABCD as \(A(x_A, y_A)\), \(B(x_B, y_B)\), \(C(x_C, y_C)\), and \(D(x_D, y_D)\).

Step 1: Reflection across the y-axis

The reflection across the y-axis transforms each point as follows:

  • \(A'(-x_A, y_A)\)
  • \(B'(-x_B, y_B)\)
  • \(C'(-x_C, y_C)\)
  • \(D'(-x_D, y_D)\)

Step 2: Translation downward by 4 units

Next, we apply the translation downward by 4 units:

  • \(A''(-x_A, y_A - 4)\)
  • \(B''(-x_B, y_B - 4)\)
  • \(C''(-x_C, y_C - 4)\)
  • \(D''(-x_D, y_D - 4)\)

Composition Transformation Mapping

To express the transformation from \(ABCD\) to \(A''B''C''D''\) in terms of composition, we can write it as:

\[ A''B''C''D'' = T_{(-4)} \circ R_{y} (ABCD) \]

Where:

  • \(R_{y}\) is the reflection across the y-axis, defined as \(R_{y}(x, y) = (-x, y)\),
  • \(T_{(-4)}\) is the translation downward, defined as \(T_{(-4)}(x, y) = (x, y - 4)\).

Thus, the overall composition would look like this:

\[ (x, y) \xrightarrow{R_{y}} (-x, y) \xrightarrow{T_{(-4)}} (-x, y - 4) \]

In terms of a single expression, you can also write this transformation as:

\[ (x, y) \mapsto (-x, y - 4) \]

This sequence of transformations will effectively map quadrilateral \(ABCD\) to \(A''B''C''D''\).