Prove that the resultant of two vector of equal magnitude is equal to either vector if the angle between the two vector is `120^(@)`

Explanation

To prove that the resultant of two vectors of equal magnitude is equal to either vector when the angle between them is \(120^\circ\), we can follow these steps:

### Step 1: Define the Vectors
Let the two vectors be \( \vec{A} \) and \( \vec{B} \), both having the same magnitude \( p \). The angle between them is given as \( \theta = 120^\circ \).

### Step 2: Use the Law of Cosines
The magnitude of the resultant vector \( \vec{R} \) can be calculated using the formula:
\[
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