Quadrilaterals & Polygons
Interior and exterior angle sums for any polygon; parallelograms and how to prove them; rectangles, rhombi, squares, trapezoids, and kites; and the quadrilateral family tree.
Builds on
Triangle congruence and the 180° angle sum (Unit 4), parallel-line angle facts (Unit 3), and the midsegment idea (Unit 5) — every quadrilateral proof splits the shape into triangles.
Lessons