Page 127 - Math Smart - 7

In this chapter
CHAPTER 6.2
Pupils should be able to:
• estimate the size of acute,
stimating. Measuring obtuse and reflex angles
to the nearest 10 degrees
• use a ruler, set square and
and Drawing Angles and draw acute, obtuse
protractor to measure
and reflex angles to the
nearest degree
6.2.1 Estimating angles

^ RECALL

Investigate!
Can you estimate the
size of the marked
O Use your protractor to find out the size of the angle between each pair angles without using a
of iines. Then label the angle between each pair of lines to show the
protractor?
amount of turn from 0°.

45" degrees

Amount
/Lm = An =
of turn
Q Identify if the angles
original position are acute, right or
obtuse angles. Then
measure them to check
your answers

Q Can you identify which pair of lines make an acute or obtuse angle?
Which pairs of lines make a reflex angle?

Now that we have seen how some angles look like at regular turns, can you
estimate the size of an angle?

Estimating the size of an angle means making an educated guess about an angle.
\
First, decide what type of angle it is.
• Does it look smaller than 90° or a right angle?
• Does it look like a right angle which is 90°?
• Does it look bigger than 90° or a right angle?
• Does it look like a straight line which is 180°?
• Does it look bigger than 180°?
• Does it look more or less than 3 right turns which is 270°?
• Does it look close to a full turn which is 360°?
/lr=