How can a similarity transformation be used determine that the AA criterion proves the dilated triangle DEF is similar to triangle ABC

Translate The dilated triangle, so one of its angles, exactly, matches the corresponding angle in the original triangle, repeat, using a different pair of angles
Reflects the triangle across the X axis, check for symmetry along with the triangleS with respect to the X axis
Center the original triangle inside the dilate, a triangle and see if the sides lengths are congruent by using the scale factor

3 answers

To show that the dilated triangle \( DEF \) is similar to triangle \( ABC \) using a similarity transformation approach, we can utilize the Angle-Angle (AA) criterion for triangle similarity. The AA criterion states that if two triangles have two pairs of corresponding angles that are equal, then the triangles are similar.

Here’s how the process using similarity transformations would work:

  1. Translate Triangle DEF:

    • Begin by translating triangle \( DEF \) so that one of its angles, say angle \( D \), matches the corresponding angle \( A \) of triangle \( ABC \). This means that vertex \( D \) is now positioned at vertex \( A \) while preserving the angles within triangle \( DEF \).
  2. Match Another Angle:

    • Next, translate triangle \( DEF \) further or perform another similar transformation such that another angle of triangle \( DEF \), say angle \( E \), now aligns with the corresponding angle \( B \) in triangle \( ABC \). After this step, angles \( A \) and \( B \) in triangle \( ABC \) correspond to angles \( D \) and \( E \) in triangle \( DEF \).
  3. Check Angles:

    • After completing the translations, now you should have two angles in triangle \( ABC \) congruent to two angles in triangle \( DEF \). According to the AA criterion, triangle \( DEF \) is similar to triangle \( ABC \) because two angles are congruent.
  4. Scaling and Reflection (if necessary):

    • You could also consider a dilation that makes triangle \( DEF \) proportionate to triangle \( ABC \). The sides of triangle \( DEF \) when compared to the sides of triangle \( ABC \) would be in the same ratio as their corresponding angles are equal. If you needed to confirm this algebraically, you could check the ratios of the lengths to ensure they maintain a constant scale factor.
    • Additionally, reflecting triangle \( DEF \) across the X-axis or any axis might help visualize the symmetry, but this is not necessary for proving similarity.
  5. Final Verification:

    • Finally, confirm that the corresponding side lengths of triangle \( DEF \) and triangle \( ABC \) maintain the scale factor, which further reaffirms their similarity, as a consequence of their equal angles.

By following the steps of translating triangle \( DEF \) to align angles with triangle \( ABC \), we can demonstrate that they are similar by using the AA criterion. Hence, the dilated triangle \( DEF \) is similar to triangle \( ABC \).

A, B, or C?

Based on the description you provided for using a similarity transformation to demonstrate that the dilated triangle \( DEF \) is similar to triangle \( ABC \), the most appropriate answer from the options you listed would likely be A:

Translate the dilated triangle, so one of its angles exactly matches the corresponding angle in the original triangle, and repeat, using a different pair of angles.

This method effectively uses the AA criterion for similarity, as it involves matching angles between the two triangles, which is a fundamental step to proving their similarity.

Options B and C involve different transformations (reflection and centering), which are not directly related to the AA criterion for establishing similarity. Therefore, option A is the correct choice.