Regular+Polygons

LESSON #5 Regular Polygons
Initial lesson posted - July 2011 Revision date - Fall 2017

** Essential Questions: ** What does it mean for a polygon to be regular and why is this word so important? What is true about the sum of the exterior angles of any polygon? A Section of the Lesson Follows
 * Purpose: ** This lesson introduces regular polygons and the location of an exterior angle.

** Polygons ** are classified by type (or have specific names). Using the Internet as a source of information is an exciting way to incorporate another technology tool to support student learning. Students could be challenged to find three definitions for a term. They can compare and contrast the definitions pointing out differences in word choices. The fact that students will use the Internet to do their homework requires the classroom teacher to know which sources are providing reliable information and which ones are suspect. Two examples are shown here (retrieved from Wikipedia, May 2011). In geometry, a polygon is traditionally a plane figure that is bounded by a closed path or circuit, composed of a finite sequence of line segments. These segments are called its **edges** or **sides**, and the points where two edges meet are the polygon's **vertices** or **corners**. The interior of the polygon is sometimes called its **body.** Polygons can be classified by noticing different properties about the sides or the interior angles. Most people recall that **regular** polygons are **equilateral** and **equiangular**. Another classification of polygons looks at if the sides intersect or not. A **regular polygon** contains sides with the same side measurement AND interior angle measurement. An irregular polygon does not restrict the side or angle measurements. If the term “regular” does not precede the term “polygon” the reader can assume that the shape could be **either** regular or irregular. A **simple polygon** is a finite sequence of connected line segments called sides that do not cross each other and share the same plane. The shapes shown in figure 5.1 and figure 5.2 are examples of simple polygons. A **complex polygon** has sides that intersect each other. The eight-sided star polygon shown in figure 5.3 is an example of a complex polygon. ** Convex ** and **concave** polygons are additional terms used to classify type of polygons. Research the definitions of these vocabulary terms. Scratch Program on irregular polygons. Irregular Polygons with Music Theme Before reading ahead, think about how you would program the turtle to draw a square or an equilateral triangle.