Where is the Maximum Intensity of Radio Signal from Two Towers?

[stphillips]

Homework Statement

Heres the question:
Two towers of a radio station are 4.00 x 10^2 m apart along and east-west line. The towers act essentially as point sources, radiating in phase at a frequency of 1.00 x 10^6 Hz. Radio waves travel at 3.00 x 10^8 m/s.

a) In which directions is the intensity of the radio signal at a maximum for listeners 20k north of the transmitter (but not necessarily directly north of it)?

b) In which directions would you find the intensity at a minimum, north of the transmitter, if the towers were to start transmitting in opposite phase?

Homework Equations

|P_nS₁ - P₂S₂| = (n -1/2)lambda

Sin theta n = (n-1/2)lambda/d

The Attempt at a Solution

I have no idea =/. Honestly I've worked on it for 30 minutes and can't even figure out where to start.

Thanks

 

[Borek]

Can you draw a triangle with both stations and the receiver? One side is given - it is the distance between antennas. Can you apply the maximum intensity condition to the lengths of two other sides?