1. Polygons and Triangles Chapter 10 Lesson 4 and 5

2. What is a polygon?
Polygons are many-sided figures, with sides that are line segments. Polygons are named according to the number of sides and angles they have.
Can be “regular” – all sides and all angles are equal to each other

3. Regular Polygons
All sides are congruent
All angles are congruent

4. Irregular Polygons Not all sides are congruent
Not all angles are congruent

5. 5 sides 5 angles 5 vertices Pentagons Regular polygon
Irregular polygon

6. Hexagons
6 sides
6 angles
6 vertices
Regular polygon
Irregular polygon

7. Heptagon
7 sides
7 angles
7 vertices
Regular polygon
Irregular polygon

8. Octagons
8 sides
8 angles
8 vertices
Regular polygon
Irregular polygon

9. Nonagon
Regular polygon
9 sides
9 angles
9 vertices
Irregular polygon

10. 10 sides 10 angles 10 vertices Decagons Regular polygon
Irregular polygon

11. Isosceles Triangles Two sides of equal length Three acute angles
Sum of angles = 180°

12. Equilateral Triangles
All sides equal length
Three acute angles
Sum of angles = 180°
Is a regular polygon

13. Scalene Triangles No sides are equal No angles are equal
May have obtuse angle
Sum of angles = 180 °

14. Right Triangle
Has one 90 ° angle
Sum of all angles 180 °

15. Acute Triangle A triangle having three acute angles.
Sum of angles = 180°

16. Obtuse Triangle A triangle having an obtuse angle.
Sum of all angles 180 °