In Maths, we often need to construct a line segment of a specifi ed length. In this example, we are constructing a line segment that is 10 cm long.
1
Draw a line of any length. Mark a point at the end of the line and label it A. This is the starting point of the line.
A 3
Place the pointer of the compass at A and mark an arc on the line with the pencil point. Mark the point where the arc and the line intersect as B .
4 2
Using a ruler, place the pointer of the compass at 0. Pull the compass out until the tip of the pencil is at the 10 cm mark.
[AB] is the required line segment of length 10 cm .
8
An arc is any smooth curve joining two points. A 10 cm Worked example 1
Indicate whether each of the coloured items below are line segments, rays or lines. Give a reason for your answer and show how the construction is written in mathematical notation.
Solution Green
Orange Purple Red
A B D C E B
If lines or arcs intersect, this means they cross over at a point.
Worked example 2
Name (using symbols and letters) three line segments using the diagram on the right.
Solution A B C
Section A Introducing concepts and building skills