Properties of Triangles

Описание: Emma and Tiana prove the Triangle Angle Sum Theorem (angles of a triangle add up to 180 degrees) and use the Triangle Inequality Theorem to determine whether three given side lengths can form a triangle.

0:00 Triangle Tiling Pattern
0:16 using tracing paper to find congruent angles of triangle's 1st angle
0:59 finding congruent angles of triangle's 2nd angle
1:08 finding congruent angles of triangle's 3rd angle
1:19 Discover relationship of triangle angles by zooming in on one section of the tiling

1:43 TRIANGLE ANGLE SUM THEOREM
1:51 Proving the Triangle Angle Sum Theorem
2:46 Applet visualization of Triangle Angle Sum Theorem proof

3:18 Discovering a relationship of triangle sides
3:43 Testing possible third side lengths of a triangle with 8" and 6" sides
4:21 Summarize findings

4:51 TRIANGLE INEQUALITY THEOREM
5:15 Given three sides, is it a valid triangle?
5:19 Example 1: 5, 3, 10
5:47 Example 2: 4, 12, 9
6:31 Example 3: 5, 2, 4
7:03 Example 4: 3, 5, 8

Sources:
CPM Integrated Math II, 1.3.4 Lesson (cpm.org)
GeoGebra Applet on Triangle Angle Sum Theorem: https://www.geogebra.org/m/rtX2pbQr