Parallel lines, quadrilaterals and triangles · Usually met around P3
Parallel lines
Never meeting, however far extended: parallel. On dot paper, compare the moves.
How to do it
Method
Never meeting, however far extended: parallel. On dot paper, compare the moves
Two segments that go 3 across and 1 down are parallel
Another way
Measure the gap
The gap is 3 squares in both places
In full
Two straight lines that never meet, however far you extend them, are parallel — like the two rails of a railway. Parallel lines are the same distance apart everywhere: measure the gap in different places and it is always the same. On dot paper, look at how each segment moves: two segments that go the same number of squares across and the same number down are parallel; if the moves differ, the lines meet somewhere when extended. To draw parallel lines, count squares on dot paper, or slide a set square along a ruler.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
The two segments in the picture are parallel.
True or false?
Show the answer and working
Answer: False
Count how far each segment goes across and down: only the same moves are parallel.
Example 2
On dot paper, a segment goes 1 squares right and 5 squares down. A segment parallel to it also goes 1 squares right. How many squares down must it go?
Show the answer and working
Answer: 5 squares
Parallel segments move the same way: 5 down as well.
Example 3
Two parallel lines are 4 cm apart in one place. How far apart are they in another place?
Show the answer and working
Answer: 4 cm
Parallel lines are the same distance apart everywhere: 4 cm.
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