Quadrilaterals & Polygons

Polygons belong to nested families defined by properties, and their angle structure can often be understood by decomposing them into triangles.

What you'll learn

  • Classify quadrilaterals using stated side, angle, and parallel-line properties.
  • Recognize nested categories such as square, rectangle, and rhombus.
  • Derive an n-gon's interior-angle sum from n−2 triangles.
  • Define regular polygons through equal sides and equal angles.
  • Use a consistent exterior turn and account for internal shared edges.

Before you start

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