Page 121 - Mathematics Coursebook

12.1 Measuring and drawing lines

12.1 Measuring and drawing lines

You must be able to use a ruler to draw and measure straight lines accurately. When you are
!is is a centimetre ruler. doing mathematical

cm 1 2 3 4 5 6 constructions, always
use a hard, sharp
pencil so that your

!e small divisions that occur in the spaces from one centimetre to the next are lines are as thin and
millimetres. clean as possible.
You need to be able to measure and draw straight lines to the nearest millimetre.

Worked example 12.1
a Measure the length of this line, correct to the nearest millimetre.
Write the measurement in i cm ii mm.
b Draw a straight line 2.7 cm long.

a i 4.2 cm Measure the line with a ruler.
ii 42 mm Make sure that the start of the line is at 0 on
the ruler. cm 1 2 3 4 5
The line fi nishes at 4 cm 2 mm, so the
answers are 4.2 cm and 42 mm.

b 1 2 3
cm

Make sure the start of the line is at 0 on the ruler. Draw the line as far as 2 cm and then 7 mm more.

) Exercise 12.1

1 Measure these lines. Give the measurements correct to the nearest millimetre.

a b

c d

e

f
Write each measurement in i cm ii mm.
2 Draw straight lines with these lengths. Write the length of each line next to it.
a 5 cm b 7.3 cm c 0.4 cm d 13.7 cm
3 Alicia has a ruler that is 15 cm long.
Explain to Alicia what she will need to do.
How can I use my 15 cm ruler to
draw a line exactly 22.3 cm long?

120 12 Constructions