RS Aggarwal Solutions for Class 7 Chapter 13 Lines and Angles, An angle is formed when two lines intersect each other. An angle involves two legs and one common vertex at which two lines meet. For example, AOD is formed when line AB and CD intersect with each other. Lines are figures that are made up of infinite points extending indefinitely in both directions. Lines are straight and have negligible depth or width. There are a variety of lines you will learn about, such as perpendicular lines, intersecting lines, transversal lines, etc. An angle is a figure in which two rays emerge from a common point. You may also come across alternate and corresponding angles in this field. The main points to be remembered by students are, the sum of all angles formed on the same side of a line at a given point on the line is 180 degrees, and the sum of all angles around a point is 360 degrees. The Chapter deals with supplementary angles, complementary angles, adjacent angles, linear pair of angles and vertically opposite angles.