1. Classifying Triangles

2. What do we remember about classifying angles? What are the different types of angles? Acute, right, obtuse, and straight

3. How are triangles classified? Triangles are classified in two ways: by their sides and their angles

4. Types of triangles classified by their sides Equilateral Isosceles Scalene

5. Types of triangles classified by their angles Acute Right Obtuse

6. Equilateral Triangles All 3 sides are congruent (Note: all 3 angles are congruent also)

7. Equilateral Triangles cont’d

8. Isosceles Triangles 2 sides are congruent (Note: base angles are also congruent)

9. Isosceles Triangle cont’d

10. Scalene Triangle No sides are congruent

11. Scalene Triangle

12. Acute Triangle All 3 angles are acute

13. Acute Triangle

14. Right Triangle Has 1 right angle

15. Right Triangle

16. Obtuse Triangle Has 1 obtuse angle

17. Obtuse Triangle

18. Multiple Classifications Triangles can be classified by both their sides and angles: Acute Isosceles Right Isosceles Obtuse Isosceles Acute Scalene Obtuse Scalene Right Scalene

19. What type of triangle does not have multiple classifications? Equilateral Triangles – all of its angles and sides are congruent, so there cannot be different types of equilateral triangles.

20. Acute Isosceles Triangle 2 sides are congruent and all angles are acute

21. Obtuse Isosceles Triangle 2 sides are congruent and one angle is obtuse

22. Right Isosceles Triangle 2 sides are congruent and one angle is a right angle

23. Acute Scalene Triangle No sides are congruent and all angles are acute

24. Obtuse Scalene Triangle No sides are congruent and one angle is obtuse

25. Right Scalene Triangle No sides are congruent and one angle is a right angle

26. Two sets of questions we should ask ourselves when classifying triangles: 1.Regarding angles: Are all 3 angles acute, or is 1 angle right or obtuse? 2.Regarding sides: Are all 3 sides congruent, are only 2 sides congruent, or are no sides congruent?

27. For you to try: what type of triangles are the following triangles?