Determine if radio waves are constructive or destructive

[PCSL]

I don't think I have to write out the problem but let me know.

There are two radio antennas emitting radio waves and a point was given to me to determine if constructive or destructive at that point.

I found the wavelength is 100m and the path difference is 200m. How can I determine if it is constructive or destructive??

edit: they are out of phase

 

[PCSL]

I'm going to bed soon and would lose if someone could help me out prior?

 

[SammyS]

Do you mean they are out of phase (by 180°) as they are transmitted at the radio antennas?

 

[PCSL]

Do you mean they are out of phase (by 180°) as they are transmitted at the radio antennas?

I would assume so but the problem does not say.

Here is the full problem:

Two out-of-phase radio antennas at x = +/- 300m on the x-axis are emitting 3MHz radio waves.Is the point (300,800) a point of maximum constructive interference, perfect destructive interference, or something in between?

It seems like this would be constructive but the answer is perfectly destructive and it makes no sense.

 

[SammyS]

If the antennas were in-phase, then there would be constructive interference.

 

[PCSL]

If the antennas were in-phase, then there would be constructive interference.

It is out-of-phase though.