|Axiom - 4:| If a transversal intersects two coplanar lines, so that a pair of corresponding angles are equal, then the two lines are parallel. Theorem - IV: If a transversal intersects two coplanar lines in such a way that pair of Alternate angles are equal, then the two lines are parallel. 'l' and 'm' are two coplanar lines. 'p' is the transversal intersecting them so that a pair of alternate angles ÐA = ÐB.l // m.Let ÐC be the vertically opposite angle to ÐA. Then, ÐA = ÐC.but ÐA = ÐB given, Therefore, ÐB = ÐC. That is the corresponding angles are equal. Therefore, by axiom-4 'l' must be parallel to 'm'. Hence l // m.Directions: Draw a pair of parallel lines and a transversal and show that the corresponding angles are equal.