Isosceles and Equilateral Angle Chaining
Equal sides force equal base angles, so spotting isosceles or equilateral triangles (often from equal radii or a diagonal) lets you chain known angles to an unknown one. Learners identify equal-side triangles inside circles and polygons and step through the angle relations. It fuses side-equality with angle-sum facts.
grade 4 GeometryMeasurement & data Draw a DiagramIdentify Subproblems
Progression (6)
g4 1. Equal point distances make isosceles triangles on a peg board Geometry
g4 2. Use equilateral 60-degree angles and equal sides GeometryMeasurement & data
g4 3. Chain isosceles base angles to find unknown angles Measurement & dataGeometry
g4 4. Two radii form an isosceles triangle; find angles Measurement & dataGeometry
g4 5. Spot equal sides to build isosceles triangles Measurement & dataGeometry
g4 6. Isosceles triangle from a rectangle diagonal GeometryMeasurement & data