Triangle ABC is a triangle on a graph. A is at (1, -3), B is at (1, -2), and C is at (4, -3). Another triangle is on the graph, triangle GHE. G is at (-2, 2), H is at (-4, 2), and E is at (-2, 5).

ABC is congruent to GHE. Describe a sequence of transformations from ABC to GHE that proves their congruence.

1 answer

To show that triangle ABC is congruent to triangle GHE through a sequence of transformations, we can follow these steps:

  1. Translation: First, we will translate triangle ABC to a new position to align one point of triangle ABC with a corresponding point of triangle GHE. We can translate triangle ABC by moving it to the left and up to match point A with point G.

    • Point A (1, -3) translates to G (-2, 2).
    • To move from A to G, we find the translation vector:
      • \( \Delta x = -2 - 1 = -3 \)
      • \( \Delta y = 2 - (-3) = 5 \)
    • So the translation vector is (-3, 5).
  2. Apply the translation: Now, we translate all points of triangle ABC by the vector (-3, 5):

    • A' (1, -3) becomes A'' (-2, 2).
    • B' (1, -2) becomes B'' (-2, 3).
    • C' (4, -3) becomes C'' (1, 2).

    After the translation, triangle A''B''C'' has the vertices:

    • A'' (-2, 2)
    • B'' (-2, 3)
    • C'' (1, 2)
  3. Reflection: Next, we need to reflect triangle A''B''C'' to match the orientation of triangle GHE. Triangle GHE has points:

    • G (-2, 2)
    • H (-4, 2)
    • E (-2, 5)

    Reflecting triangle A''B''C'' across the line x = -2, the transformation will adjust the coordinates of points B'' and C'' as follows:

    • A'' will remain unchanged at (-2, 2).
    • B'' (-2, 3) reflects to (-4, 3).
    • C'' (1, 2) reflects to (-5, 2) (Note: Change in x-value since it's a reflection across a vertical line).

    However, note that we need to ensure the corresponding points match, specifically (H should correspond to B'' and E to C'').

Through a combination of translation and reflection, we can show that:

  1. Translate -3 units left and 5 units up.
  2. Reflect left across x = -2.

Conclusion:

Thus, triangle ABC can be transformed into triangle GHE by first translating it and then reflecting it across the line x = -2. Hence, triangles ABC and GHE are congruent through these transformations.