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A triangle is one of the basic shapes in geometry. In this unit, students investigate the relationship among the sides and between the sides and angles of a given triangle including special segments such as median and altitude. They also investigate conditions necessary to have congruent triangles, use appropriate notation to describe two congruent triangles, and examine theorems that establish congruency between two triangles.

Geometry: Triangles Activities

Title Type

Corresponding Parts of Congruent Triangles

Explore corresponding parts of congruent triangles.

Alignments  Standards  |  Textbook  
  • 7159

Angle-Side Relationships

Investigate some necessary conditions for creating a triangle.

Alignments  Standards  |  Textbook  
  • 6965

Triangle Inequality Theorem

Given the measures of any three segments, will you always be able to make a triangle?

Alignments  Standards  |  Textbook  
  • 5819

Triangle Sum Theorem

Investigate the special relationship of the angles of a triangle.

Alignments  Standards  |  Textbook  
  • 6934

Special Segments in Triangles

Create four special segments from a given vertex in a triangle and identify relationships among the special segments and the angles they form.

Alignments  Standards  |  Textbook  
  • 6726

Congruent Triangles

This activity is intended to provide students with an opportunity to discover three methods of proving triangles congruent: SSS, SAS, and ASA.

Alignments  Standards  |  Textbook  
  • 5333

Side-Side-Angle: The Ambiguous Case

Experiment with segment lengths and angle measures.

Alignments  Standards  |  Textbook  
  • 6648
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