What Phase Difference Leads to the Largest Amplitude?

[kavamo]

Homework Statement

Two waves with identical frequency but different amplitudes A1 = 6.0 cm and A2 = 2.0 cm, occupy the same region of space (are superimposed).

(a) At what phase difference does the resulting wave have the largest amplitude?

Homework Equations

I have found the amplitude of the resulting wave (8.0 cm) which was the second part of the problem) but am not sure how to calculate the phase difference. The formula in my books is:

d1-d2/lamda(wavelength)

The Attempt at a Solution

The problem is I don't know/understand how to solve for the distances. Can anyone point me in the right direction?

Thanks.

 

[rl.bhat]

Resultant amplitude is maximum when the phase difference is 2*n*pi, where n = 0, 1, 2, ..etc.

 

[kavamo]

Thank you for the assist.

kavamo