When two lines intersect, the opposite (X) angles are equal. In the diagram above, the two green angles are equal and the two yellow angles are equal.

In this video we will learn about the Complementary angles, Supplementary angles, Adjacent angles, Linear Pair, Vertically opposite angles and Proof for vertically opposite angles being equal.

Parallel lines are straight lines which have the same direction and so never meet. Arrowheads show lines are parallel. A straight line that cuts a pair of parallel lines is called an intersecting ...

ii) (Prove) If two lines intersect, the vertically opposite angles are equal. iii) (Motivate) Results on corresponding angles, alternate angles, and interior angles when a transversal intersects two ...

Class 9 Maths Chapter 6 Lines and Angles is available here for download in PDF format. We have provided here the latest edition of the chapter which is published by the NCERT on its official website.