area. the amount of surface covered by each shape is called its area. which one of these carpets...
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Area
The amount of surface covered by each shape is called its area.
Which one of these carpets takes up more floor space?They have the same area.
The usual way of measuring area is to find the number of squares a shape covers
1 cm
1cm
Here we have a square measuring 1 cm by 1 cm
We say the square has an area of 1 2cm
1 cm
1cm
2 cm
2 cm
Here we have a square measuring 2 cm by 2 cmIf we place it on some centimetre squared paper we can see it covers 4 squares
We say the square has an area of 4 2cm
What is the area of the following rectangles?
A B C
AB
C
Placing each one onto centimetre paper we have:
The area of rectangle A is 6 2cmThe area of rectangle B is 24 2cmThe area of rectangle C is 12 2cm
AB
C3 cm
2 cm
6 cm
4 cm
2 cm
6 cm
The area of a rectangle
Length = 3 cm Width = 2 cm
The area of rectangle A is 23 2 6cm
Length = 6 cm Width = 4 cm
The area of rectangle B is 26 4 24cm
Length = 2 cm Width = 6 cm
The area of rectangle C is 22 6 12cm
Length (l)
Width (w)Area length width
lw
The area of a rectangle
Area of a triangleDraw a triangle onto squared paperDraw a rectangle around it
Notice the area of the rectangle is base height2Area 14 8 112cmbh
base
height
Cut out the shaded area and place onto the left part of the triangle.Cut out the shaded area and place onto the right part of the triangle.
What do you notice?
height
We notice the area of the triangle is 1
base height2
21 1
Area 14 82 2
56cmbh
base
height
Area of a triangle
base
height
Area of a triangle
1
2A bh
Area of a parallelogram
base
height
base
height
A parallelogram is a quadrilateral, which its opposite sides are parallel but are of unequal length
Consider the shaded part and cut it off and place it on the other side.
What do you notice?
The area of the parallelogram is base height.
base (b)
height (h)
Area of a parallelogram
The area of a parallelogram is base height
bh
h
a
b
Split the trapezium into two triangles
Area of a trapezium
Area of triangle A1
2ah Area of triangle B
1
2bh
Split the trapezium into two triangles
h
b
h
a
AB
Area of trapezium 1 1 1
2 2 2ah bh a b h
Area of a trapezium
To find the area of a trapezium you must add together the two parallel sides, multiply by the height and divide by 2.
1
2A a b h
h
a
b
The area of a kite
Draw a kite onto squared paperDraw on diagonal length aDraw on diagonal length b.Cut out shaded triangle.Place the triangle on the other side.Cut out the shaded triangle.Place this triangle on the other side.
a
b
Your diagram should look like this.
a
b
The area of a kite
1
2a
b
The length (l) is 1
2a
The width (w) is b
The area
1
2
lw
ab
What do you notice? We now have a rectangle
b
a
The area of a kite
Area of a kite is half the product of its diagonals
1
2A ab
length (l)
width (w)
A lw1
2A bh
base (b)
height (h)
base (b)
height (h)
A bh
h
a
b
1
2A a b h
b
a 1
2A ab
Area of Shapes
Rectangle Triangle Parallelogram
Trapezium Kite
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