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 GMD Draw a DiagramIdentify Subproblems
Progression (6)
4-2 1. Equal point distances make isosceles triangles on a peg board 4.G.A.2
4-2 2. Use equilateral 60-degree angles and equal sides 4.G.A.24.MD.C.7
4-2 3. Chain isosceles base angles to find unknown angles 4.MD.C.74.G.A.2
4-2 4. Two radii form an isosceles triangle; find angles 4.MD.C.74.G.A.2
4-2 5. Spot equal sides to build isosceles triangles 4.MD.C.74.G.A.2
4-2 6. Isosceles triangle from a rectangle diagonal 4.G.A.24.MD.C.7