3.4 Congruent Triangles
Triangle Sums
I.SectionObjectives
- Identify interior and exterior angles in a triangle.
- Understand and apply the Triangle Sum Theorem.
- Utilize the complementary relationship of acute angles in a right triangle.
- Identify the relationship of the exterior angles in a triangle.
II.Cross-curricular-HangGliders
- Have students examine the triangles in the image from Wikipedia.
- This is Figure 04.01.01.
- http://www.en.wikipedia.org/wiki/Hang_gliding
- Ask students what they notice about the number of triangles that are in the hang glider.
- Then have the students identify all of the different angles of the triangles, also include the interior and exterior
angles. - There are angles created by the strings too.
- Complete this as a whole class discussion.
III.TechnologyIntegration
- Have students complete a google search on triangles in nature.
- There they will find hundreds of different images of how triangles are found in nature.
- Ask the students to look for triangles and assign them the task of finding a real example of triangles in nature.
- Have students bring in these examples the next day and show them to the class.
IV.NotesonAssessment
- This class is a discussion class.
- You want the students to see the connection between the different angles of the triangles both interior and
exterior. - Although it is not directly mentioned, you can draw students back to the Triangle Sum Theorem and explain
how the measurement of the angles still equal 180◦. - Also make note of any congruent triangles and why they are important to the hang glider being able to fly.
- If the top sails weren’t congruent, what would happen then?
Congruent Figures
I.SectionObjectives
Chapter 3. Geometry TE - Enrichment