THE WORLD OF

POLYGONSLESSON 4

ACTIVITY:BIRDSEYE VIEW

ACTIVITY:BIRDSEYE VIEW

ACTIVITY:BIRDSEYE VIEW

ACTIVITY:BIRDSEYE VIEW

IS SHAPE 1 A

POLYGON?

ACTIVITY:BIRDSEYE VIEW

IS SHAPE 2 A

POLYGON?

ACTIVITY:BIRDSEYE VIEW

IS SHAPE 3 A

POLYGON?

DEFINITIONPolygon, in geometry, a

simple closed two-dimensional figure formed by the joining of three or more straight line segments, called SIDES.

DEFINITION

A figure is simple if it extends in no more than two directions from any point and closed if its starting point is the same as its endpoint.

DEFINITION

These restrictions require that the sides of a polygon not cross each other and that pairs of sides intersect at their ENDPOINTS, which are called VERTICES.

POLYGONS POLYGONS ARE NAMED AND ARE NAMED AND

CLASSIFIED CLASSIFIED ACCORDING TO ACCORDING TO

THEIR NUMBER OF THEIR NUMBER OF SIDES.SIDES.

EXAMPLESTRIANGLE RECTANGLE

PENTAGON

EXAMPLESHEXAGON

REGULAR POLYGONS3 SIDES 4 SIDES 5 SIDES 6 SIDES

7 SIDES 8 SIDES 9 SIDES 10 SIDES

REGULAR POLYGONSALL ANGLES ARE EQUAL and ALL SIDES ARE EQUAL.

REMEMBER

All polygons have an equal number of sides and vertices.

EXAMPLE

TRIANGLE

- 3 SIDES.- 3 VERTICES- 3 ANGLES

Polygons are also classified as CONVEX and NONCONVEX.

NONCONVEX

Polygons are also classified as CONVEX and NONCONVEX.

CONVEX

What is the difference between CONVEX and NONCONVEX

POLYGONS?

CONVEX

NONCONVEX

A POLYGON IS CONVEX IF A

SEGMENT JOINING ANY 2 POINTS OF

THE POLYGON LIES COMPLETELY

INSIDE THE POLYGON.

CONVEX

OTHERWISE THE POLYGON IS NONCONVEX .

NONCONVEX

EXERCISES• TELL WHETHER OR NOT EACH

OF THE FOLLOWING IS A POLYGON.

QUIZ• TELL WHETHER A POLYGON IS

CONVEX OR NOT.

POLYGONSPOLYGONSPOLYGONSPOLYGONSLESSON 5LESSON 5

RECALL

All polygons have an equal number of sides and vertices.

TRIANGLE

QUADRILATERAL

PENTAGON

HEXAGON

HEPTAGON

OCTAGON

NONAGON

DECAGON

POLYGON PARTS

POLYGON PARTS

Side - one of the line segments that make

up the polygon.

Vertex - point where

two sides meet. Two or

more of these points

are called vertices.

POLYGON PARTS Diagonal -

a line connecting

two vertices

that isn't a side.

POLYGON PARTS Interior Angle - Angle

formed by two adjacent sides inside the polygon.

Exterior Angle - Angle

formed by two adjacent sides outside the polygon.

TRIANGLE