Area and Perimeter

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Area and Perimeter

• Yes you do need to write this.

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AREA

• The amount of space inside a
  2-dimensional object.
• Measured in square units cm2, m2, mm2
• Not to be confused with

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Perimeter

• The distance around a two dimensional object.
• Measured in normal units eg. cm, m, mm

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Some shapes have there own formulas for area

• Yes, you do need to draw these as well.

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Rectangle

• b
• a

• Area of a rectangle
• ab (length x width)
• Perimeter 2a 2b
• 2(a b)

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No, you dont have to try one.
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Parallelogram

• a
• b
• a is the vertical height

• Parallelogram quadrilateral with two pairs of
  parallel sides.
• Area ab
• Can not work out the perimeter with the
  information given.

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One to try

• 6cm
• 7cm

• Area 6 x 7 42 cm2

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Triangle Area ½ bh( h is the vertical
height)

• h h
• b b

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Trapezium(a quadrilateral with one pair of
parallel sides)

• a
• h
• b

• Add together the parallel sides, divide by 2 and
  then multiply by the distance between them.
• Area (a b) x h
• 2

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Example

• 2cm
• 10cm
• 5cm

• Area (2 5) x 10
• 2
• 3.5 x 10
• 35 cm2

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Compound Shapes

• These are shapes made by joining two or more
  shapes together.
• To find the area, find the area of the smaller
  shapes and add together.

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Example.

• 7cm
• 10cm
• 8cm
• 3cm

• 7cm
• 2cm
• 8cm
• 3cm

X
Y
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Example.
Area of X 7 x 2 14 cm2 Area
of Y 3 x 8 24 cm2 Total area
14 24 38 cm2

7cm
2cm
8cm 3cm
X
Y
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Last one.Find the shaded area

• 10cm
• 10cm
• 
  

• Area of square 10 x 10
• 100 cm2
• A. of triangle ½ x 3 x 4
• 6 cm2
• Shaded area 100 6
• 94 cm2

3cm
3cm
4cm
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The only part left is circles(always a circle
question)

• And then its volume.