Answer:
<em>Each boat are </em><em>43.86</em><em> miles from the lighthouse.</em>
Step-by-step explanation:
From the diagram, at point A the lighthouse is placed and at B, C two boats are placed.
As the two boats are equidistant from a lighthouse, so AB=AC.
Hence, ΔABC is an isosceles triangle.
The angle formed between the two boats, with the lighthouse as the vertex, measures 40°. So m∠A=40°.
The altitude to the base of an isosceles triangle bisects the vertex angle.
Hence, 
The altitude to the base of an isosceles triangle bisects the base.
Hence, 
In ΔABE,


As AB=AC, so AC=43.86