Lesson 5: 3.5 Isosceles & Equilateral Properties
Duration of Days: 2
Lesson Objective
Apply properties of isosceles base angles and equilateral triangles
What special properties do base angles have?
Base Angles
CCSS.G.CO.C.10
I DO: Fold a piece of paper in half to cut out a perfectly symmetrical isosceles triangle, showing how base angles map onto each other.
WE DO: Practice identifying the "base" vs the "legs" on rotated triangles on the smartboard.
YOU DO: Calculate missing base angles independently.
Utilize symmetry as a shortcut for calculations.
DOK 2
Support (Low): Provide guided, step-by-step calculation sheets
Formative Assessment
GeoGebra
Paper for folding/cutting