1. Lesson 8.2 – 8.3 Angles, Triangles and Quadrilaterals
Essential Question: How do you classify angles, triangles and quadrilaterals?

2. Before we start… What is the angle measure of a straight angle?
What is the angle measure of a right angle?

3. How do you classify an angle?
By it’s angle measure: Acute: Less than 90° Right: Is 90° Obtuse: Greater than 90°

5. How do you classify a triangle?
By its angles
Acute
Right
Obtuse
By its sides
Equilateral
Isosceles
Scalene

6. What is an acute triangle?
A triangle has three acute angles

7. What is a right triangle?
A triangle that has one right angle

8. What is an obtuse triangle?
A triangle that has one obtuse angle

9. What is an equilateral triangle?
A triangle that has three equal sides

10. What is an isosceles triangle?
A triangle that has two sides of equal length

11. What is a scalene triangle?
A triangle that has no sides of equal length

12. Geometric figures are named using the vertices of each angle (clockwise or counterclockwise). Tick marks in a drawing show that side lengths are equal. Arc marks show that angles are equal.

14. Classify the triangle by: - its angles - its side lengths

15. Classify the triangle by: - its angles - its side lengths

16. Classify the triangle by: - its angles - its side lengths

17. Classify the triangle by its side lengths:
7 cm, 9 cm, 7 cm
11 ft, 11 ft, 11 ft
4 in, 5 in, 6 in

18. How many degrees are in a triangle?
Every triangle has three angles that add up to 180°.

19. Find the missing angle in the triangle. Then classify it by its angles.

20. Find the missing angle in the triangle. Then classify it by its angles.

21. Find the missing angle in the triangle. Then classify it by its angles.

22. What is a quadrilateral?
A closed figure with four sides that are line segments

23. How do you classify a quadrilateral?
By its sides and angles
Trapezoid
Parallelogram
Rhombus
Rectangle
Square

24. What is a trapezoid?
A quadrilateral with exactly 1 pair of parallel sides

25. What is a parallelogram?
A quadrilateral with two pairs of parallel sides

26. What is a rhombus?
A parallelogram with 4 sides of equal length

27. What is a rectangle?
A parallelogram with 4 right angles

28. What is a square?
A parallelogram with 4 sides of equal length and 4 right angles

29. Classify the quadrilateral.

30. Classify the quadrilateral.

31. Classify the quadrilateral.

32. Classify the quadrilateral.

33. Classify the quadrilateral.

34. Classify the quadrilateral.

35. Angles in a Quadrilateral
The angles in a quadrilateral add up to 360°

36. Find the value of x.

37. Find the value of x.

38. Find the value of x.

39. Find the value of x.

40. Find the value of x.

41. Find the value of x.

42. How do you classify angles, triangles and quadrilaterals?

43. Ticket Out the Door
Find the value of x.