1. Classifying Polygons
Lesson 9-3

2. Classifying Triangles
Triangles have 3 sides and can be classified or named based on 2 things—their angles and their sides.

3. Triangles By angles: Acute—all three angles are acute.
Less than 90 degrees
Right—has one right or 90 angle.
Obtuse—has one obtuse angle.
Greater than 90 degrees

4. Triangles By sides: Equilateral—all three sides are equal.
Isosceles—two sides are equal.
Scalene—all three sides are different.

5. Try This
Give two names for the following:

6. Try This
Give two names for the following:
Scalene, right

7. Try This
Give two names for the following:

8. Try This
Give two names for the following:
Equilateral, acute

9. Try This
Give two names for the following:

10. Try This
Give two names for the following:
Isosceles, acute

11. Try This
Give two names for the following:

12. Try This
Give two names for the following:
Scalene, obtuse

13. Quadrilaterals
Quadrilaterals have FOUR sides. These are examples of quadrilaterals:

14. Classifying Quadrilateral
All four sided figures are quadrilaterals. They may or may not be symmetrical.

15. Quadrilaterals
Parallelograms have 2 sets of parallel lines.

16. Quadrilaterals Parallelograms have 2 sets of parallel lines.
Rectangles have parallel lines and 90
angles.

17. Quadrilaterals Parallelograms have 2 sets of parallel lines.
Rectangles have parallel lines and 90
angles.
Rhombus has four equal sides.

18. Quadrilaterals
Squares have four equal sides and four 90 angles.

19. Quadrilaterals Squares have four equal sides and four 90 angles.
Trapezoids have exactly one pair of parallel lines.

20. Try This
Name all the names that apply for this shape:

21. Try This Name all the names that apply for this shape:
Quadrilateral, parallelogram, rectangle

22. Try This
List all the names for this shape:

23. Try This List all the names for this shape:
Quadrilateral, parallelogram, rhombus

24. Try This
List all the names for this shape:

25. Try This
List all the names for this shape:
Quadrilateral, trapezoid

26. Bonus question
Are all squares also rectangles?

27. Bonus question
Are all squares also rectangles? Yes

28. Bonus question Are all squares also rectangles? Yes
Are all rectangles also squares?

29. Bonus question Are all squares also rectangles? Yes
Are all rectangles also squares? No