Geometry: Perimeter and Area

Can You Name the Shape?

Geometry: Perimeter and Area

New Vocabulary:Perimeter: The distance around a

geometric figure.Formula : An equation that shows a

relationship among certain quantities.Area: The measure of the surface enclosed

by a figure.

WidthDefinition:

How wide a figure is from side to side.

LengthDefinition:The measure of the distance across an figure.

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PerimeterTo calculate the

perimeter of any shape, just add up “each” line segment of the “fence”.

Perimeter 3 in

2 in 2 in

3 in

Perimeter 3 in

2 in 2 in

3 in

P= 2 + 3 + 2 + 3 = 10 in

You can find the perimeter of a rectangle by adding all of the sides together.

Find the Perimeter Using a Formula

PERIMETER OF ARECTANGLE

P=2l+2w

2 in.

3 in.Perimeter of a RectangleP=2l+2wP=2(3 in.) + 2 (2in.)P=6 in. + 4 in.P=10 in.

PERIMETER OF ATRIANGLE

P=s +s +s1 2 3

Perimeter of a TriangleP=s + s + s

1 2 3

P=8cm+10cm+6cm

P= 24 cm

8cm

6cm

10cm

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RememberSquares ALL sides are equal…so if

they give you one side, you know ALL the sides

Length=the Largest sideIf they “leave” numbers out, they

are equal to their opposite side. If they give you the bottom of a square/rectangle type shape then the top is the same

Finding area of an irregular figureBox the object

in then count the length and the width of the “box”.

Example:Length = 4Width = 5

Find The Perimeter

What is the perimeter of this figure?

Area is the amount of surface space that a flat object has.

Area is reported in the amount of square units.

AREASquare units means that “that” many squares fit inside that

shape (if measured in feet…it’s feet…if meters…it’s meters. In this example the area is 4 square units…note 4 squares fit)

1

2 units (ft, in, m)

2

3 4

Count the number of blue

squares to determine the area of that

surface.

The area is equal to 9 squares.

Area = 15 square feet

What is the area of this surface if each square is equal to one foot?

Count the number of squares.

1 2

3

4 5 6 7 8

9 10 11 12 13 14

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Two neighbors build swimming pools. This is what the pools look like. Which family has the pool with the

bigger swimming area?

The area of Family A’s pool is 8 square units.

The area of Family B’s pool is 7 square units.

Therefore, Family A has the pool with the bigger swimming area.

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Area of Squares/RectanglesLength x Width=Area

2

Length(2) x Width(2) = 4 square units

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Parallelogram AreaArea=Base x Height(Area=length x width)

BASE (length)

Height (width)

8

5

Base 8 x Height 5 = Area 40

The diagonal line is NOTthe height!!!