In a `DeltaABC`, `sum (b + c) cos A=`

Options

A. a+b+c
B. a+b-c
C. a-b+c
D. none of these

Explanation

To solve the problem, we need to find the value of \( \sum (b + c) \cos A \) in triangle \( ABC \).

### Step-by-Step Solution:

1. **Understanding the Expression:**
We start with the expression \( \sum (b + c) \cos A \). This means we need to evaluate \( (b + c) \cos A + (c + a) \cos B + (a + b) \cos C \).

2. **Expanding the Expression:**
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