I think we would die because we need the earth atmosphere to live...
Answer:
The path difference between the two waves should be one-half of a wavelength.
Explanation:
For the destructive interference to form at point P the path difference between the two waves should be
= 
where n can be any integer starting from 0,1,2....
therefore we can say that
If the maximum destructive interference is to occur at point P, The path difference between the two waves should be one-half of a wavelength.
<span>In the decades after the departure of the last U.S. combat troops from Vietnam in March 1973 and the fall of Saigon to communist North Vietnamese forces in April 1975, Americans have been unable to agree on how to characterize the long, costly and ultimately unsuccessful U.S. military involvement in Indochina.</span>
The majority of the countries in the world use the same calendar but a few use their own.:)