RS Aggarwal Solutions for Class 9 Chapter 7 “Lines and Angles”, the pairs of lines are nothing but the two lines, which may be intersecting or parallel or perpendicular. Angles: The region between two infinitely long lines pointing a specific direction (ray) from a common point (or vertex) is termed as an angle. The rays forming an angle are known as an arm, and the endpoint is the vertex of the angle. There are different kinds of angles, namely reflex angle, obtuse angle, right angle, complete angle, straight angle and acute angle. The different types of lines mainly include skew lines, vertical lines, parallel lines, horizontal lines and perpendicular lines. Lines and Angles have a wide range of applications in various fields like designing of roads, buildings, sports facilities and lines are mainly used to plan the line of business, which gives information about the services and products offered by the company.