Page 128 - Math Smart - 7

o Spotlight

Paper Pocket Protractor GROUP WORK
Use this link to find out
What you need: thick art paper, scissors, a pencil, coloured pencils and a
more about making a
protractor.
paper pocket protractor.
Instructions
Q Get into groups of 3 or 4.
Q Each member of the group has to draw two shapes on the paper. Each
shape must have at least a right angle, an angle of 45°, and an angle of
30° or 60°.
Q Fold a piece of paper to make corners that are 45°, 30°, 60° and 90°.
Q Then use it to measure the angles in your shapes.

You can use the special angles learnt in previous stages to help you in your
estimations.

N B

Example 1

Estimate the size of ABC.
We can use a clock face
^ Use a protractor to
to help us estimate the
find out the actual
angle.
size. It is 33°.
This estimation is
acceptable because
it is within 10° of
the actual size of the
angle.
Solution
This is an acute angle. The size of this angle is between 0° and 90°.

It looks closer to 30° than 45°.

So, we can estimate that the size of angle ABC is about 30°.

Angles and Their Properties