4.7Equilateral Triangles
Quick Answer
An equilateral triangle has all three sides congruent and all three angles equal to 60°. It is a special case of an isosceles triangle. Equilateral Triangle Theorem: equilateral ↔ equiangular.
Essential Question
What properties make equilateral triangles special, and how do those properties follow from the Isosceles Triangle Theorem?
Learning Goals
- 1State the properties of equilateral triangles.
- 2Prove that an equilateral triangle is equiangular.
- 3Find missing side lengths and angle measures in equilateral triangles.
- 4Identify equilateral triangles in composite figures.
Key Vocabulary
Equilateral triangle
A triangle with all three sides congruent.
Equiangular triangle
A triangle with all three angles congruent (each 60°).
Equilateral Triangle Theorem
If a triangle is equilateral, then it is equiangular (all angles = 60°), and vice versa.
Full lesson content coming soon
Worked examples, guided practice problems, a workbook, quiz, and downloadable PDF resources will be added to this lesson in Phase 2. The learning goals and vocabulary above reflect the complete lesson scope.