Polygons
Polygons is a Grade 8 geometry skill in Saxon Math Course 3, Chapter 2, where students identify and classify closed 2D figures with three or more straight sides by their properties including number of sides, angle measures, and regularity. This foundational vocabulary supports perimeter, area, and similarity work across middle and high school geometry.
Key Concepts
New Concept This course builds your mathematical foundation step by step. We begin with fundamental shapes like polygons , which are closed plane figures with straight sides. What’s next This lesson is your starting point. Next, you'll master how to name, classify, and compare different polygons using concepts like congruence and similarity.
Common Questions
What defines a polygon?
A polygon is a closed plane figure formed by three or more straight line segments (sides) that connect at vertices. The sides must not cross each other.
What are polygons named by?
Polygons are named by their number of sides: triangle (3), quadrilateral (4), pentagon (5), hexagon (6), heptagon (7), octagon (8), nonagon (9), decagon (10).
What is a regular polygon?
A regular polygon has all sides equal in length and all interior angles equal in measure. A square and an equilateral triangle are examples.
What is the formula for the sum of interior angles of any polygon?
The sum of interior angles of a polygon with n sides is (n minus 2) times 180 degrees.
Where are polygons studied in Grade 8?
Polygons are covered in Saxon Math Course 3, Chapter 2: Number and Operations and Geometry.