Quiz Wed'

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4/28

• Quiz Wed.

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Homework Issues
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14. A farmer has a fence that encloses a square
pot with an area of 36 sq. meters.

• If the farmer uses this fence to enclose a
  circular flower garden, what will the area of the
  garden be?
• There are two ways to think about this.
• How do we answer these?

Way 2
Way 1
36 in2
Uses the same fence
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10.3
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1. Surface Area

• The surface area is the area needed to cover all
  of the faces of a 3-D object.

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• Use some of the 3-D manipulatives (the colorful
  ones we used before)
• Play around with finding the surface areas of
  some shapes.
• How did you go about doing this?

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• Notice that looking at the nets of the object
  makes it easier to think about the surface areas.

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2. Surface area of a prism the sum of all the
areas of all of its faces.

• Find the surface areas of the prisms shown below.
• Work with a partner. What do you think?

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Again, we can look at nets.
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12
12
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• Can we find an easier way to determine the
  surface area?

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Notice that the length of this rectangle is the
perimeter of the base.
Height 12
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• The Surface area of a prism
• 2Bph
• Where B is the area of the base, p is the
  perimeter of the base, and h is the height of the
  prism.

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3. The Surface Area of Cylinders

• How can we do this?
• How do we make a net for this?

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• Surface area of a cylinder

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4. The Surface Area of Pyramids

• Were only going to work with pyramids whose
  triangular lateral faces are congruent. The apex
  is above the center of the base.
• Find the SA of the pyramid below.

l5 cm, s6cm
What is this angle here?
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Area of each triangle ½(6)(5)
l5, s6
Notice that 4(6) is the perimeter of the square.
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• The SA of a pyramid B 1/2 pl
• B Area of Base
• p perimeter
• l slant height

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Find the surface area of the below pyramid
s6 in, and the height of the pyramid is 1 ft.
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5. The Surface area of a Cone

• Lets use what we have from the pyramid
• SA of pyramid B 1/2 pl

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• SA of a cone

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• Find the SA of

7 in
5 in
3 in
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6. The Surface Area of Spheres.