# 3.12 - Polygons

The student will

a)  define polygon;

b)  identify and name polygons with 10 or fewer sides; and

c)  combine and subdivide polygons with three or four sides and name the resulting polygon(s).

### BIG IDEAS

• So that I can solve problems in real-life and in geometry using representations of polygons
• So that I can recognize the shapes that are all around me

### UNDERSTANDING THE STANDARD

• A polygon is a closed plane figure composed of at least three line segments that do not cross.
• Polygons may be described by their attributes (e.g., sides and vertices).  Line segments form the sides of a polygon and angles are formed by two line segments coming together at a vertex of a polygon.
• A rectangle, square, trapezoid, parallelogram, and rhombus are all classified as quadrilaterals.

### ESSENTIALS

The student will use problem solving, mathematical communication, mathematical reasoning, connections and representation to

• Define polygon. (a)
• Classify figures as polygons or not polygons. (a)
• Identify and name polygons with 10 or fewer sides in various orientations:
• triangle is a three-sided polygon;
• quadrilateral is a four-sided polygon;
• pentagon is a five-sided polygon;
• hexagon is a six-sided polygon;
• heptagon is a seven-sided polygon;
• octagon is an eight-sided polygon;
• nonagon is a nine-sided polygon; and
• decagon is a ten-sided polygon. (b)

• Combine no more than three polygons, where each has three or four sides, and name the resulting polygon. (c)
• Subdivide a three-sided or four-sided polygon into no more than three parts and name the resulting polygon(s). (c)

### KEY VOCABULARY

Updated: Aug 22, 2018