Three waves from three coherent sources meet at some point .
Resultant amplitude of each is `A_0`. Intensity corresponding to `A_0 is I_0`. Phase
difference between first wave and the second wave is `60^@` . Path difference
between first wave and the third wave is `lambda/3.` The first wave lags behind in phase
angle from second and the third wave. Find resultant intensity at this point.

Explanation

To find the resultant intensity at the point where three coherent waves meet, we can follow these steps:

### Step 1: Determine the Phase Differences
We have three waves:
- Wave 1 (W1) has a phase of \(0^\circ\).
- Wave 2 (W2) has a phase of \(60^\circ\) relative to W1.
- Wave 3 (W3) has a phase difference of \(120^\circ\) relative to W1 (since the path difference is \(\lambda/3\), which corresponds to a phase difference of \(2\pi/3\) or \(120^\circ\)).

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