Suppose that you are given a system of two equations of the following form
`Acosphi=Bv_(1)-Bv_(2)costheta`…………..(1)
`A sinphi=Bv_(2)sin theta`………..(2)
Show that,
`A^(2)=B^(2)(v_(1)^(2)+v_(2)^(2)-2v_(1)v_(2)costheta)`

Explanation

To solve the given problem, we will manipulate the two equations step by step to arrive at the desired result.

**Given equations:**
1. \( A \cos \phi = B v_1 - B v_2 \cos \theta \) (Equation 1)
2. \( A \sin \phi = B v_2 \sin \theta \) (Equation 2)

**Step 1: Square both equations.**

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