Find the angle between the lines whose direction ratios are a, b, c and `b - c , c - a , a - b`.

Explanation

To find the angle between the lines with direction ratios \( a, b, c \) and \( b - c, c - a, a - b \), we can use the concept of the dot product of vectors. The angle \( \theta \) between two vectors can be determined using the formula:

\[ \cos \theta = \frac{\vec{A} \cdot \vec{B}}{|\vec{A}| |\vec{B}|} \]

### Step-by-Step Solution:

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