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Area of Shapes. The area of a shape is the space it occupies. Write down the name of each shape. A powerpoint presentation by Carmelo Ellul Head of Department (Mathematics). Parallelogram. Trapezium. Square. Rectangle. Circle. Triangle. Area of Shapes. Click button to select topic.

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area of shapes
Area of Shapes
  • The area of a shape is the space it occupies.
  • Write down the name of each shape.

A powerpoint presentation by

Carmelo Ellul

Head of Department (Mathematics)

Parallelogram

Trapezium

Square

Rectangle

Circle

Triangle

slide2

Area of Shapes

  • Click button to select topic.

Square

Rectangle

Parallelogram

Triangle

Trapezium

Circle

End Show

the square
The Square

Area = lxb

e.g.Find the area of a square of

side 3.5 cm.

Discuss

and work out

this example

together

with your friend.

b

breadth

A = l x b

A = 3.5 cmx 3.5 cm

= 12.25 cm2

l

length

the rectangle
The Rectangle

Area = lxb

e.g.Find the area of a rectangle of

length 3.5 cm and height 80 mm.

Discuss

and work out

this example

together.

Since units must be the same:

10 mm =1 cm

80 mm = 80 mm ÷ 10 = 8 cm

A = l xb

A = 3.5 cmx 8 cm

= 28 cm2

b

l

the parallellogram

3.8 cm

10.3 cm

h

b

The Parallellogram

Area = bxh

e.g.Find the area of a parallelogram

correct to 1 d.p.

height

h

base

b

A = b xh

A = 10.3 cmx 3.8 cm

= 39.14 cm2

= 39.1 cm2

Discuss

and work out

this example

together.

the triangle

A

4 cm

B

C

11.7 cm

h

h

h

b

b

b

Area of = ½b  h

Area of parallelogram = b  h

Area of = ½ area of parallelogram

The Triangle

e.g.Find the area of triangle ABC

correct to the nearest cm2.

Area = ½b h

h

height

b

base

A = ½b xh

A = ½ x 4 cmx 11.7 cm

= 23.4 cm2

= 23 cm2

Discuss

and work out

this example

together.

the trapezium

8.5 cm

6 cm

12 cm

Rotate the trapezium

The Trapezium

e.g.Find the area of the trapezium.

Area = ½h(a + b)

Length of side a

a

h

height

Length of side b

b

h = 6cm, a = 8.5 cm, b = 12 cm

A = ½h(a + b)

A = ½x 6 cm x (8.5 cm + 12 cm)

= ½x 6 cm x 20.5 cm

= 61.5 cm2

Decide about the values

of a, b and h

to find the area.

b

a

h

a

b

Area of 1 trapezium is half h(a + b)

 Area of trapezium = ½h(a + b)

Area of parallelogram = h(a + b)

The 2 trapeziums form a parallelogram

Copy the trapezium

the circle
The Circle

Area = pr2

e.g.The diameter of a circle is 19 cm. Find, correct to nearest whole

number, the area of a circle.

r = 19 cm ÷ 2

= 9.5 cm.

A = p r2

= px9.5 cm x9.5 cm

= 283.5 cm2

= 284 cm2

Radius

Find the radius first

and then work out

this example

together.

r

Centre

Remember:

the radius

of a circle is

half the diameter.

the circle9
The Circle

Area = pr2

e.g.The diameter of a circle is 19 cm. Find, correct to nearest whole

number, the area of a circle.

r = 19 cm ÷ 2

= 9.5 cm.

A = p r2

= px 9.5 cm x9.5 cm

= 283.5 cm2

= 284 cm2

r

Remember:

the radius

of a circle is

half the diameter.

End Show