## G-CO.8

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

- Illustrations

Khan Academy Videos

- Congruent Triangles and SSS
- SSS to Show a Radius is Perpendicular to a Chord that it Bisects
- Other Triangle Congruence Postulates
- Two column proof showing segments are perpendicular
- Finding Congruent Triangles
- More on why SSA is not a postulate
- Perpendicular Radius Bisects Chord
- Congruent Triangle Proof Example
- Congruent Triangle Example 2

Khan Academy Practice

- Congruency postulates
- Congruent triangles 1
- Congruent triangles 2

NCTM Illuminations

- Congruence Theorems

Shmoop

- Explanation
- 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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