Extension
Working with dimensions l Measuring 2-dimensional shapes
Measuring 2-dimensional shapes
For this activity you need to know how to calculate:
•
•
•
perimeter
circumference
area.
If you need some assistance, discuss your options with your teacher.
Find the perimeter and area of the following five shapes.
Remember:
• Measurements of single dimensions such as length, perimeter and circumference
are given in metres (m), mm, cm, and km.
• Areas of 2D shapes are given in square units such as: mm², cm², m², hectares (ha)
and km².
a)
15 cm
36 cm
Perimeter
© WestOne Services 2010
Area
COMM1085
Page 1 of 6
Extension
Working with dimensions l Measuring 2-dimensional shapes
b)
Tip: work out the dimensions of lengths not given, and practise your skill
of dividing up the shape into separate shapes to calculate perimeter and
total area.
36 m
10 m
18 m
26 m
7m
Perimeter
© WestOne Services 2010
Area
COMM1085
Page 2 of 6
Extension
Working with dimensions l Measuring 2-dimensional shapes
c)
Tip: Area of a triangle = B x H
2
5 cm
4 cm
Perimeter
© WestOne Services 2010
Area
COMM1085
Page 3 of 6
Extension
Working with dimensions l Measuring 2-dimensional shapes
d)
Tip: pi = 3.14
Circumference of circle
=
xD
π
Area of circle
=
x r²
π
45 m
20 m
Perimeter
© WestOne Services 2010
Area
COMM1085
Page 4 of 6
Extension
Working with dimensions l Measuring 2-dimensional shapes
e)
Jess wants to lay paving in her backyard, which has a large tree. She wants to
keep the tree, and measures its circumference as 2.36 m. Help Jess work out
the area to be paved.
Note: The shaded area in the diagram below is where the tree sits and will not
be paved.
Tip: C = pi x diameter so, D = C
π
7m
9m
Perimeter
© WestOne Services 2010
Area
COMM1085
Page 5 of 6