The document discusses formulas for calculating the areas of parallelograms, triangles, and trapezoids. It uses animations to show how the area of a parallelogram can be derived by sliding one half of the figure over to form a rectangle, with the formula A=bh. Similarly, it shows how the area of a triangle can be derived by rotating one half and forming a parallelogram, resulting in the formula A=1/2bh.

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

2. AREA OF A PARALLELOGRAM
b
h
Welcome. Today you’re going to discover
the formula for area of a parallelogram.
Click to Continue

3. AREA OF A PARALLELOGRAM
b
h
To do this let’s cut the left triangle and…
Click to Continue

4. AREA OF A PARALLELOGRAM
h b
h
slide it…
Click to Continue

5. AREA OF A PARALLELOGRAM
h
b
h
slide it…

6. AREA OF A PARALLELOGRAM
h
b
h
slide it…

7. AREA OF A PARALLELOGRAM
h
b
h
slide it…

8. AREA OF PARALLELOGRAM
b
h
…thus, changing it to a rectangle.
What is the area of the rectangle?
A bh A b h A 2bh

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

10. AREA OF A PARALLELOGRAM
b
h
Since the area of the rectangle and parallelogram are
the same, just rearranged, what is the formula for the
area of this parallelogram?
A bh A b h A 2bh

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

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

13. AREA OF A TRIANGLE
Hello. You will now be
discovering the formula
h for area of a triangle.
Click to Continue
b

14. AREA OF A TRIANGLE
? Let’s divide the triangle
so that we divide the
height in two.
?
b Click to Continue

15. AREA OF A TRIANGLE
Remember, we divided
the height into two equal
?
parts.
Now take the top and
rotate…
?
b Click to Continue

16. AREA OF A TRIANGLE
?
rotate…
?

17. AREA OF A TRIANGLE
?
rotate…
?
b

18. AREA OF A TRIANGLE
?
rotate…
?
b

19. AREA OF A TRIANGLE
?
rotate…
?
b

20. AREA OF A TRIANGLE
?
?
rotate…
b

21. AREA OF A TRIANGLE
?
?
b
…until you have a parallelogram.
How would you represent the height of this parallelogram?
1
h 2h 2 h

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

23. AREA OF A TRIANGLE
?
b
What is the area of this parallelogram?
1
A bh A 2 hb A 2bh

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

25. AREA OF A TRIANGLE
The area of this triangle
would be the same as
the parallelogram.
Therefore, the formula for
h
the area of a triangle is…
what?
b
1
A bh A 2 hb A 2bh

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