wat are co interior angles and their measure

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When two lines are crossed by another line (i.e. transversal), then the pair of angles on one the same side of the transversal but inside the two lines are called co-interior angles (or consecutive interior angles).

 

 

In the given figure, a and b are co-interior angles and c and d are co-interior angles. Here, a + b > 180� and c + d < 180�

If the two lines l and m are parallel, then the sum of two co-interior angles is always 180� i.e., a + b = 180� and c + d = 180�.