How much cardboard does it take to make a cereal box? Have you ever wondered?
-
Upload
eric-barnett -
Category
Documents
-
view
217 -
download
1
Transcript of How much cardboard does it take to make a cereal box? Have you ever wondered?
How much cardboard does it take to make a cereal box?
Have you ever
wondered?
Surface Area- the sum of the areas of all the faces
Do you see the RED
face?
4 in.
7 in.
10 in.
What are the dimensions of this rectangle?10 in.
4 in.
Do you see another face that is just like the RED face?
Where is it located?
4 in.
7 in.
10 in.
Yes, it’s on the back.
10 in.
4 in.
10 in.
4 in.
Now there are 2 rectangles
40 in2
40 in2 that each have an
area of 40 sq. in.
4 in.
7 in.
10 in.
Do you see the BLUE face?
What are the dimensions of this rectangle?
4 in.
7 in.
Do you see another face that is just like the BLUE face?
Where is it located?
4 in.
7 in.
10 in.
Yes, it’s on the left side.
4 in.
7 in.7 in.
4 in.
Now there are 2 rectanglesthat each have an area of 28 sq. in.
28 in2
28 in2
4 in.
7 in.
10 in.
Do you see the GREEN face?
What are the dimensions of this rectangle?
10 in.
7 in.
Do you see another face that is just like the GREEN face?
Where is it located?
4 in.
7 in.
10 in.
Yes, it’s on the bottom.
10 in.
7 in.
10 in.
7 in.
Now there are 2 rectanglesthat each have an area of 70 sq. in.
70 in2
70 in2
Now we just need to add all the areas of the sides together.
+ +
++ 70 in2
28 in2
40 in2
40 in2
28 in2
70 in2
The total Surface Area for this rectangular prism is
40 + 40 + 28 + 28 + 70 + 70 =
276 in2
It’s your turn to try
one!
Find the surface area.
6 cm
3 cm2 cm
Area of top and bottom:
3 cm x 2 cm = 6 cm22
Since there are two of these shapes,
6 cm2 x 2 = 12 cm12 cm22
Find the surface area.
6 cm
3 cm2 cm
Area of front and back:
3 cm x 6 cm = 18 cm2
Since there are two of these shapes,
18 cm2 x 2 = 36 cm36 cm22
Find the surface area.
6 cm
3 cm2 cm
Area of both sides:
6 cm x 2 cm = 12 cm2
Since there are two of these shapes,
12 cm2 x 2 = 24 cm24 cm2
Find the surface area.
6 cm
3 cm2 cm
Now add up the answers
12 cm12 cm22
36 cm36 cm22
+24 cm+24 cm22
72 cm72 cm22
Formula for Surface Area of Rectangular Prisms
SA = 2(lw) + 2(lh) + 2(wh)
width
height
length
Formula for Surface Area of a Cube
SA = 6(s2)
side
side
sideSince all dimensions of a cube are the same, you only need to know the length of one side.
End
of
day 1
How much metal is used to make a soup can?
Surface Area of a cylinder = Area of top + Area of bottom + Area of the side
TOP
BOTTOM
SIDE
Area of a circle is πr2.
Since there are 2 circles that make up the
net of a cylinder then,
the area is 2(πr2).
The area of a rectangle is the product of the two sides. One side is the height of the can, the other side is the circumference of the circle, since the label wraps once around the can.
h
C=2πr
So the area of So the area of the rectangle the rectangle
is (2is (2ππr)h.r)h.
C
Add those two parts together and you have the formula for the surface area of a cylinder.
Surface Area of a Cylinder =
2(π r 2) + (2 π r)hCircles + Rectangle
Example 1:Example 1:
Find the surface area of this cylinder.
r = 3 cm
h = 6 cm