Answer:
Distance will be 49.34 m
Step-by-step explanation:
We have given wavelength

Diameter of the antenna d = 2.7 m
Range L = 7.8 km = 7800 m
We have to find the smallest distance hat two speedboats can be from each other and still be resolved as two separate objects D
We know that distance is given by

So distance D will be 49.34 m