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Geometry . Notes Section 4-3. What you’ll learn. How to name and label corresponding parts of congruent triangles. How to identify congruence transformations. Vocabulary. Congruent triangles Congruence transformations. Definition of Congruent Triangles.
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Geometry Notes Section 4-3
What you’ll learn. . . . • How to name and label corresponding parts of congruent triangles. • How to identify congruence transformations.
Vocabulary • Congruent triangles • Congruence transformations
Definition of Congruent Triangles First . . . Congruence is a relationship between at least 2 triangles. • Two triangles are congruent if and only if their corresponding parts are congruent.
Two triangles are congruent if and only if their corresponding parts are congruent. • Corresponding • Partsof • Congruent • Trianglesare • Congruent
Example #1: Identify the congruent triangles in each figure.
Example #2: Identify the congruent triangles in each figure.
3 Interesting Facts about Congruent Triangles. . . .(theorems). . . . First . . . Congruence of triangles is reflexive. Second . . . Congruence of triangles is symmetric. Third . . . Congruence of triangles is transitive.
Congruence of triangles is reflexive. If you have a triangle, it is congruent to itself.
Congruence of triangles is symmetric. If ΔABCΔDEF,then ΔDEFΔABC .
Congruence of triangles is transitive. If ΔABCΔDEF and ΔDEFΔGHI then ΔABCΔGHI.
Definition of Congruence Transformation. . . . Recall the transformations slides, flips, and turns. Will these transformations change the shape of a triangle? NO. If you slide, flip, or turn a triangle the resulting triangle is congruent to the original.
Example Problem #3: • Describe the congruence transformation between the two triangles as a slide, a flip, or a turn. Then name the congruent triangles.
Have you learned. . . . • How to name and label corresponding parts of congruent triangles. • How to identify congruence transformations. • Assignment: • Non-Proof: Worksheet 4-3 • Proof: p.195(10-34Even)