I've had a go, but im really not confident about it being correct......

Let R be the distance from the hive to the nearest flowering tree.

R > 1 it there aren't any flowering trees in a circle D with a radius of 1 (with the hive being at the centre (0,0).

The area of D, km

where r is the radius of the circle.

So

Similarly

Then

Am I way off with this?