Two straight lines, which exist in a plane
, are intersected by a straight line
, which is called as a transversal line. This transversal line creates total 8 angles on these two lines and each line has 4 angle like a traversal line XY, which intersect two lines ‘AB’ and ‘DE’ and creates 8 angles.
Angles on straight line
AB: $\angle$i, $\angle$j, $\angle$k, $\angle$l
Angles on Straight Line
DE: $\angle$m, $\angle$n, $\angle$o, $\angle$p
Now, when two angles from different groups of straight lines are defined in opposite side like $\angle$l from AB and $\angle$n from DE, $\angle$k from AB and $\angle$m from DE are called as alternate interior angles.
We use following steps for evaluating alternate interior angle from an angle pair:
First we calculate one alternate interior angle from one straight line like we have a straight line PQ, whose one alternate interior angle is equal to 50 degree.
After evaluation of one alternate interior angle, now it’s easy to find out other alternate interior angle by using following rule:
Alternate Interior Angle 1 = Alternate Interior Angle 2
Suppose, we have a traversal line LN, which intersect two straight lines GH and IJ, and if one alternative interior angles is equal to 110 degree, then the other alternate interior angle is,
Alternate interior Angle 1 = alternate interior angle 2 = 110 degree
Therefore, other alternate interior angle is equal to ‘110 degree’.