Math Problem Statement

In the diagram, DE || BC. Complete the steps to prove that ∆ADE is similar to ∆ABC.

Solution

In the given diagram, we need to prove that ADE\triangle ADE is similar to ABC\triangle ABC by showing that two pairs of angles are congruent.

Step-by-step reasoning:

  1. Angle DAE\angle DAE is a common angle between both triangles ADE\triangle ADE and ABC\triangle ABC.

    • So, DAE=BAC\angle DAE = \angle BAC.
  2. Since DEBCDE \parallel BC and ABAB is a transversal line, corresponding angles are equal:

    • ADE=ABC\angle ADE = \angle ABC.
  3. By the AA (Angle-Angle) similarity criterion, if two corresponding angles are equal, the triangles are similar.

    • Thus, ADEABC\triangle ADE \sim \triangle ABC.

Drag and Drop Answer:

  • DAE=BAC\angle DAE = \angle BAC (common angle)
  • ADE=ABC\angle ADE = \angle ABC (corresponding angles, DEBCDE \parallel BC)
  • ADEABC\triangle ADE \sim \triangle ABC (Two respective angles are equal)

Would you like further details on the reasoning or any clarifications?

Here are some related questions for practice:

  1. How do you prove triangles are similar using the AA criterion?
  2. What other criteria besides AA can be used to prove triangle similarity?
  3. If two triangles are similar, what can be said about their corresponding sides?
  4. What are alternate interior angles, and how do they help in proving similarity?
  5. Can the similarity of triangles be used to find unknown side lengths?

Tip: In geometry, parallel lines often help identify congruent corresponding or alternate angles.

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Math Problem Analysis

Mathematical Concepts

Geometry
Triangle Similarity
Parallel Lines

Formulas

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Theorems

AA Similarity Theorem
Corresponding Angles Postulate

Suitable Grade Level

Grades 8-10