1. 8.3 Area of Squares and Rectangles

2. Area The amount of surface covered by a figure is its area.
Area is measured in square units.
in² (inches squared)
ft² (square feet)

3. Area of a Square
Area of a Square= side x side
(side)²
A = s²

4. Find the area of the square

5. Area of a Rectangle Area of a Rectangle = base x height A = bh
Height, h
Base, b

6. Find the area
16 ft
24 ft

7. A = 54 in² h
9 in
Find the height.

8. Which of the following areas are you trying to find?
AREAS OF POLYGONS
Which of the following areas are you trying to find?
Parallelogram
Triangle
Trapezoid

9. AREA OF A PARALLELOGRAMb h
Welcome. Today you’re going to discover the formula for area of a parallelogram.
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10. AREA OF A PARALLELOGRAMb h
To do this let’s cut the left triangle and…
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11. AREA OF A PARALLELOGRAMb h h
slide it…
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12. AREA OF A PARALLELOGRAMh b h
slide it…

13. AREA OF A PARALLELOGRAMh b h
slide it…

14. AREA OF A PARALLELOGRAMh b h
slide it…

15. AREA OF PARALLELOGRAM b h …thus, changing it to a rectangle.
What is the area of the rectangle?

16. You Answered Correctly.
Congratulations!!!
You Answered Correctly.
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17. AREA OF A PARALLELOGRAMb h
Since the area of the rectangle and parallelogram are the same, just rearranged, what is the formula for the area of this parallelogram?

18. You Answered Correctly.
Congratulations!!!
You Answered Correctly.
Click to continue.

19. The next slide will take you into discovering the area of a triangle.
Do you wish to continue?
Yes No

20. Hello. You will now be discovering the formula for area of a triangle.
Click to Continue b

21. Let’s divide the triangle so that we divide the height in two.
AREA OF A TRIANGLE b ?
Let’s divide the triangle so that we divide the height in two.
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22. AREA OF A TRIANGLE b ?
Remember, we divided the height into two equal parts.
Now take the top and rotate…
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23. AREA OF A TRIANGLE ?
rotate… ?

24. AREA OF A TRIANGLE ?
rotate… ? b

25. AREA OF A TRIANGLE ?
rotate… ? b

26. AREA OF A TRIANGLE ?
rotate… ? b

27. AREA OF A TRIANGLE ? ?
rotate… b

28. AREA OF A TRIANGLE ? b …until you have a parallelogram.
How would you represent the height of this parallelogram?

29. Remember, you divided the height in two.
AREA OF A TRIANGLE ? ? ? ? b b
Remember, you divided the height in two.
Click to Continue

30. What is the area of this parallelogram?
AREA OF A TRIANGLE ? b
What is the area of this parallelogram?

31. You Answered Correctly.
Congratulations!!!
You Answered Correctly.
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32. AREA OF A TRIANGLE
The area of this triangle would be the same as the parallelogram. Therefore, the formula for the area of a triangle is… what? h b

33. You Answered Correctly.
Congratulations!!!
You Answered Correctly.
Click to continue.

34. The next slide will take you into discovering the area of a trapezoid.
Do you wish to continue?
Yes No

35. Hi. Let’s derive the formula for the area for a trapezoid.
AREA OF A TRAPEZOID
Hi. Let’s derive the formula for the area for a trapezoid.
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36. Remember, there are two different bases on a trapezoid.
AREA OF A TRAPEZOID h
Remember, there are two different bases on a trapezoid.
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37. AREA OF A TRAPEZOID ?
First divide the trapezoid horizontally so the height is divided in two.
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38. Remember, we divided the height in two. Now, rotate…
AREA OF A TRAPEZOID ? ?
Remember, we divided the height in two. Now, rotate…
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39. AREA OF A TRAPEZOID ? ?
rotate…

40. …until, you have a parallelogram.
AREA OF A TRAPEZOID ? ?
…until, you have a parallelogram.
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41. How would you represent the height of the parallelogram?
AREA OF A TRAPEZOID ?
How would you represent the height of the parallelogram?

42. Remember, we divided the height in two.
AREA OF A TRAPEZOID ? ?
Remember, we divided the height in two.
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43. How would you represent the base of the parallelogram?
AREA OF A TRAPEZOID ?
How would you represent the base of the parallelogram?

44. The new base is made by connecting the top and bottom bases.
AREA OF A TRAPEZOID ? ?
The new base is made by connecting the top and bottom bases.
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45. How would you represent the area of this parallelogram?
AREA OF A TRAPEZOID ?
How would you represent the area of this parallelogram?

46. It is improper to add subscripts. Try again.
AREA OF A TRAPEZOID
It is improper to add subscripts. Try again.
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47. AREA OF A TRAPEZOID
Reminder. In order to add before multiplying you must use grouping symbols.
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48. AREA OF A TRAPEZOID h
The area of this trapezoid is the same as the parallelogram. What is the formula for area of a trapezoid?

49. You Answered Correctly.
Congratulations!!!
You Answered Correctly.
Click to continue.

50. Sorry!!! Try again.
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51. AREAS OF POLYGONS
Once you have finished with the handouts and tests you will have completed the unit on areas of parallelograms, triangles, and trapezoids. Have a good day.
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