Solution

Given,

Distance between coherent sources A and B (d) = 5 m,
The wavelength of source (λ) = 6 m,

We have, for constructive interference, a path difference = nλ = 0, 1, 2, .... --------- (i)

Here, in this case, it is impossible to have a path difference (λ) or more because the sources of separation is less than the wavelength of the radio waves. So, only n = 0 is possible.

Then, from equation (i),

AC - BC = 0 x λ
Or, x - ( 5 - x) = 0
Or, x = 2.5 m

i.e., the maximum brightness point between A and B is 2.5 m away from A towards B.