Lesson (1-6): Polygons_ p: 45

A polygon is a closed figure whose sides are all segments that intersect only at their endpoints

examples

polygon not a polygon:curved

not a polygon:open

Names of polygons

number of sides

polygon

3 triangle

4quadrilateral

5pentagon

6hexagon

7heptagon

8octagon

9nonagon

10decagon

quadrilateral

hexagon

Convex and Concave Polygons

- If all lines drawn across a polygon cut it in exactly 2 points, then it is convex

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- If one line drawn across it cuts it in more than 2 points, then it is concave

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-If all sides and angles of a polygon are equal, then it is regular

Regular and Irregular Polygons

- If not all sides and angles of a polygon are equal, then it is irregular

It is the sum of the measures of the sides of the polygon

Perimeter

22 2

2

22

22

10

10

5 5 P= 2+2+10+2+2+5+2+2+10+2+2+5=46