With the centre $\mathrm{O},$ draw two circles of radii $4 \mathrm{c}\mathrm{m}$ and $2.5 \mathrm{c}\mathrm{m}.$

Draw any circle and mark point $\mathrm{B}$ such that:

$\mathrm{B}$ is in the interior of the circle.

Draw any circle and mark points $\mathrm{C}$ such that: 

$\mathrm{C}$ is in the exterior of the circle.