NCERT Solutions for Class 9 Maths Unit 6
Lines and Angles Class 9
Unit 6 Lines and Angles Exercise 6.1, 6.2, 6.3 Solutions
Line
A line is a collection of points that extends without limit in a straight formation. A line can be named by a single letter, like line l, or it can be named according to two points that it contains, like line AB. The second way of naming a line indicates an important property common to all lines: any two points in space determine a line.
Angles
Technically speaking, an angle is the union of two rays (lines that extend infinitely in just one direction) that share an endpoint (called the vertex of the angle). The measure of an angle is how far you must rotate one of the rays such that it coincides with the other.