Теория:

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\(m\) and \(n\)  are any two non-parallel lines and \(l\)  is another line intersecting them at \(A\)   and \(B\). 
  
Such intersecting line (\(l\)) is called as transversal line.
  
A transversal line is a line that intersects two lines at distinct points.
  
NOTE:
  
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The line \(l\)   is not a transversal to the lines \(m\)   and \(n\),    but it is a transversal to the pair of lines \(m\) and \(o\) , \(n\) and \(o\). 
  
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Line \(l\) does not intersect the lines \(m\) and \(n\) at distinct points. So, it is not a transversal line.