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Angles of Polygons.

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Presentation on theme: "Angles of Polygons."— Presentation transcript:

1 Angles of Polygons

2 What does the word “polygon” mean?
Let's Discuss What does the word “polygon” mean? What is the smallest number of sides a polygon can have? What is the largest number of sides a polygon can have?

3 Triangle Octagon Quadrilateral Nonagon Pentagon Decagon Dodecagon
Hexagon n-gon Heptagon Hendecagon

4 Hip Bone’s connected to the… Classifying Polygons
Polygons with 3 sides… Triangles Polygons with 4 sides… Quadrilaterals Polygons with 5 sides.. Pentagons But wait we have more polygons Polygons with 6 sides… Hexagons Polygons with 7 sides… Heptagons Polygons with 8 sides… Octagons But still we have more polygons Polygons with 9 sides… Nonagons Polygons with 10 sides… Decagons Polygons with 12 sides… Dodecagons And now we have our polygons

5 Important Terms A VERTEX is the point of intersection of two sides F A
CONSECUTIVE VERTICES are two endpoints of any side. F A B C D E A segment whose endpoints are two nonconsecutive vertices is called a DIAGONAL. Sides that share a vertex are called CONSECUTIVE SIDES.

6 Polygons are named by listing its vertices consecutively.
F E D

7 More Important Terms EQUILATERAL - All sides are congruent
EQUIANGULAR - All angles are congruent REGULAR - All sides and angles are congruent

8 Three more important terms
Interior Angles Exterior Angles SUPPLEMENTARY the SUM of an interior angle and it’s corresponding exterior angle = 180o

9 It’s what’s inside that counts 
Finding and using the interior angle measures of polygons

10 What is the sum of the measures of the interior angles of a triangle?
180° 180° 180° What is the sum of the measures of the interior angles of any quadrilateral? 360°

11 Sum of measures of interior angles
# of triangles Sum of measures of interior angles # of sides 1(180) = 180 3 1 2(180) = 360 4 2 3 3(180) = 540 5 6 4 4(180) = 720 n-2 (n-2) 180 n

12 If a convex polygon has n sides, then the sum of the measure of the interior angles is (n – 2)(180°)

13 If you know the sum of the angles of a regular polygon, how can you find the measure of one of the congruent angles? Regular Polygon Interior angle sum Measure of one angle Triangle 180o Quadrilateral 360o Pentagon Hexagon Heptagon Octagon Decagon Dodecagon n-gon


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