Explain how the criteria for triangle congruence (ASA, SAS, and SSS) follow from the definition of congruence in terms of rigid motions.

Internet Resources (Videos, Websites, etc.)

Illustrative Mathematics Project

  1. Illustrations

Khan Academy Videos

  1. Congruent Triangles and SSS
  2. SSS to Show a Radius is Perpendicular to a Chord that it Bisects
  3. Other Triangle Congruence Postulates
  4. Two column proof showing segments are perpendicular
  5. Finding Congruent Triangles
  6. More on why SSA is not a postulate
  7. Perpendicular Radius Bisects Chord
  8. Congruent Triangle Proof Example
  9. Congruent Triangle Example 2

Khan Academy Practice

  1. Congruency postulates
  2. Congruent triangles 1
  3. Congruent triangles 2

NCTM Illuminations

  1. Congruence Theorems


  1. Explanation
  2. Quiz

Texas Instruments

Math Nspired: Circles: Properties of Tangents
Explore properties of tangent lines and how they differ from secant lines. Device: TI-Nspire(TM) CAS, TI-Nspire(TM)
Math Nspired: Congruent Triangles
This activity is intended to provide students with an opportunity to discover three methods of proving triangles congruent: SSS, SAS, and ASA. Device TI-Nspire, TI-Nspire CAS, TI- Nspire Navigator
Math Nspired: Exploring Perpendicular and Angle Bisectors
Create angle bisectors and explore the relationships between the two angles that are formed by the bisector. Device: TI-Nspire(TM) CAS, TI-Nspire(TM)
Math Nspired: Triangles: Corresponding Parts of Congruent
Explore corresponding parts of congruent triangles. Device: TI-Nspire(TM) CAS, TI-Nspire(TM)
Math Nspired: Triangles: Side-Side-Angle
Experiment with segment lengths and angle measures. Device: TI-Nspire(TM) CAS, TI-Nspire(TM)
Math Nspired: Triangles: Triangle Inequality Theorem
Given the measures of any three segments, will you always be able to make a triangle? Device: TI-Nspire(TM) CAS, TI-Nspire(TM)

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