4.11. Equilateral Triangles http://www.ck12.org
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- Find the measures ofxandy.
Summary
This chapter begins with the Triangle Sum Theorem, showing that the sum of the angles in a triangle is a constant.
The definition of congruency is presented and from that foundation the chapter presents other important theorems
related to congruent triangles, such as the Third Angle Theorem and the SSS, SAS, ASA, AAS and HL Triangle
Congruency Theorems.
Chapter Keywords
- Interior Angles
- Vertex
- Triangle Sum Theorem
- Exterior Angle
- Exterior Angle Sum Theorem
- Remote Interior Angles
- Exterior Angle Theorem
- Congruent Triangles
- Third Angle Theorem
- Reflexive Property of Congruence
- Symmetric Property of Congruence
- Transitive Property of Congruence
- Side-Side-Side (SSS) Triangle Congruence Postulate
- Included Angle
- Side-Angle-Side (SAS) Triangle Congruence Postulate
- Angle-Side-Angle (ASA) Congruence Postulate
- Angle-Angle-Side (AAS or SAA) Congruence Theorem
- HL Congruence Theorem
- Base Angles Theorem
- Isosceles Triangle Theorem
- Base Angles Theorem Converse
- Isosceles Triangle Theorem Converse
- Equilateral Triangles Theorem
Chapter Review
For each pair of triangles, write what needs to be congruent in order for the triangles to be congruent. Then, write
the congruence statement for the triangles.