The Rectangle Method Finding Area of Triangles and Parallelograms.
11.1 area of triangles and parallelograms
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Which of the following areas are you trying to find? Parallelogr am Triangle Trapezoid AREAS OF POLYGONS
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Transcript of 11.1 area of triangles and parallelograms
Which of the following areas are you trying to find?
Parallelogram Triangle Trapezoid
AREAS OF POLYGONS
AREA OF A PARALLELOGRAM
Welcome. Today you’re going to discover the formula for area of a parallelogram.
h
b
Click to Continue
AREA OF A PARALLELOGRAM
To do this let’s cut the left triangle and…
h
b
Click to Continue
slide it…
AREA OF A PARALLELOGRAM
h
h b
Click to Continue
slide it…
AREA OF A PARALLELOGRAM
h
h
b
slide it…
AREA OF A PARALLELOGRAM
h
h
b
slide it…
AREA OF A PARALLELOGRAM
h
hb
…thus, changing it to a rectangle.
What is the area of the rectangle?
AREA OF PARALLELOGRAM
h
b
bhA hbA bhA 2
Congratulations!!!
You Answered Correctly.
Click to continue.
AREA OF A PARALLELOGRAM
Since the area of the rectangle and parallelogram are the same, just rearranged, what is the formula for the
area of this parallelogram?
h
b
bhA hbA bhA 2
Congratulations!!!
You Answered Correctly.
Click to continue.
The next slide will take you into discovering the
area of a triangle.
Do you wish to continue?
Yes No
AREA OF A TRIANGLE
Hello. You will now be discovering the formula for area of a triangle.h
bClick to Continue
AREA OF A TRIANGLE
Let’s divide the triangle so that we divide the
height in two.
b
?
?
Click to Continue
AREA OF A TRIANGLE
Now take the top and rotate…
b
?
?
Click to Continue
Remember, we divided the height into two equal
parts.
AREA OF A TRIANGLE
rotate…
?
?
AREA OF A TRIANGLE
?
?
b
rotate…
AREA OF A TRIANGLE
?
?
b
rotate…
AREA OF A TRIANGLE
?
?
b
rotate…
AREA OF A TRIANGLE
?
?
b
rotate…
AREA OF A TRIANGLE
??
b
…until you have a parallelogram.
How would you represent the height of this parallelogram?
h2 h21h
AREA OF A TRIANGLE
??
b
b
?
?
Remember, you divided the height in two.
Click to Continue
AREA OF A TRIANGLE
?
b
What is the area of this parallelogram?
bhA hbA 21 bhA 2
Congratulations!!!
You Answered Correctly.
Click to continue.
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
bhA hbA 21 bhA 2
Congratulations!!!
You Answered Correctly.
Click to continue.
