CK-12 Geometry-Concepts

4.6. SSS Triangle Congruence http://www.ck12.org

Example B

Write a two-column proof to show that the two triangles are congruent.

Given:AB∼=DE

Cis the midpoint ofAEandDB.

Prove: 4 ACB∼= 4 ECD

TABLE4.3:

Statement Reason

1.AB∼=DE

Cis the midpoint ofAEandDB

Given

2.AC∼=CE,BC∼=CD Definition of a midpoint

3. 4 ACB∼= 4 ECD SSS Postulate

Make sure that you clearly state the three sets of congruent sides BEFORE stating that the triangles are congruent.

Prove Move:Feel free to mark the picture with the information you are given as well as information that you can

infer (vertical angles, information from parallel lines, midpoints, angle bisectors, right angles).

Example C

Find the distances of all the line segments from both triangles to see if the two triangles are congruent.

Begin with 4 ABCand its sides.