The Earth E and the Moon M can both be considered as isolated point masses at their centres. The mass of the Earth is 
and the mass of the Moon is 
. The Earth and the Moon are separated by a distance of 
, as shown in the figure below (not drawn to scale).
P is a point, on the line joining the centres of E and M, where the resultant gravitational field strength is zero. Point P is at a distance 
from the centre of the Earth. Show that is approximately 
.
