NCERT Book Class 9 Mathematics Chapter 6 Measuring Space: Perimeter and Area

Measuring Space:
6 Perimeter and Area

In Fig. 6.1, you see
athletes assembled at
the start of a 4 × 100 m
relay race. The tracks
are laid out, and the
athletes are all set to go
racing down the tracks.
Do you notice that the
athletes are not at the
same starting line?
Fig. 6.1: Athletes at the start of 4 × 100 m relay race

Those in the outer lanes seem to be starting ahead of those in the
inner lanes while the finish line is the same for all of them. What could
be the reason for this? The distance between the starting points of
adjacent lanes is called the ‘stagger’. Notice that the stagger continues
all the way to the outermost lane. Do you think the stagger gives
anyone (those in the outer lanes or in the inner lanes) an unfair
advantage? Why or why not? On what basis can the organisers work
out the length of the stagger between lanes?

Think and Reflect
In my school, the playground is too small to have a 400 m track, so the
school constructed a 200 m track instead. Does this mean that we need
a smaller stagger for the race tracks in my school (i.e., smaller than the
stagger used in the Olympics), for the same 4 × 100 m relay race?

To answer the question about the lane staggers required on a
4 × 100 m athletics track, we need to know how to find the length
around a circle.

Chapter 6.indd 118 4/15/2026 3:02:30 PM