Activity 32: Problems and Puzzles

Think back to the Activity with the problem on Routes. This involved looking at the stonework and tracing along the lines of the joins between the stones.

In that case the lines were all at right angles to each other.

Consider this problem: if you draw four intersecting lines, what will be the largest number of crossings?



Try this. Is the one shown the largest number of crossings or intersections
you could get?

Start with two lines, them three and then four and five.





Complete this table:

Lines	Crossings
2
3
4
5
6
7

See if you can find a rule that will let you complete the crossings for six and seven without having to draw them.