Math Problem Statement

Given: AB ≅ CD. Prove: AC ≅ BD. Note: Quadrilateral properties are not permitted in this proof.

Solution

The problem provided in the image gives the following:

Given:

  • ABCD\overline{AB} \cong \overline{CD}

To Prove:

  • ACBD\overline{AC} \cong \overline{BD}

From the diagram, points AA, BB, CC, and DD are collinear with AD\overline{AD} being a straight segment.

Step-by-step proof:

  1. Given: ABCD\overline{AB} \cong \overline{CD}
    Reason: This is the information provided in the problem.

  2. AC and BD are segments of the straight line AD:

    • The segments AC\overline{AC} and BD\overline{BD} can be considered as composed of smaller parts. Specifically, AC=AB+BC\overline{AC} = \overline{AB} + \overline{BC} and BD=BC+CD\overline{BD} = \overline{BC} + \overline{CD}.
      Reason: By segment addition postulate.
  3. Substitute the congruent parts:

    • Since ABCD\overline{AB} \cong \overline{CD}, substitute into the equations for AC\overline{AC} and BD\overline{BD}.
      This gives:
      AC=AB+BC\overline{AC} = \overline{AB} + \overline{BC} and
      BD=AB+BC\overline{BD} = \overline{AB} + \overline{BC}.
      Reason: Substitution property of congruence.
  4. Conclude that ACBD\overline{AC} \cong \overline{BD}:

    • Since AC\overline{AC} and BD\overline{BD} are composed of the same segments, they must be congruent.
      Reason: Definition of congruent segments (equal parts sum to equal wholes).

Thus, you have proven that ACBD\overline{AC} \cong \overline{BD}.


Would you like more details on any step? Let me know if you have questions!

Here are 5 related questions:

  1. What is the segment addition postulate?
  2. How do you prove two segments are congruent?
  3. Can this proof be adapted using coordinate geometry?
  4. What are other ways to prove congruence between line segments?
  5. How does congruence differ from equality in geometry?

Tip: In geometry, when proving congruence between segments or shapes, always rely on clear postulates and properties, such as segment addition and substitution.

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Math Problem Analysis

Mathematical Concepts

Congruence
Segment Addition Postulate
Geometric Proofs

Formulas

Segment Addition Postulate: AC = AB + BC, BD = BC + CD

Theorems

Congruent Segments
Substitution Property of Congruence

Suitable Grade Level

Grades 9-10