A protractor is a tool used to measure angles in degrees. It has a semi-circular shape with markings from 0° to 180°. A protractor helps in accurately drawing and measuring angles for geometric constructions and is commonly used in mathematics and engineering to determine the size of an angle.

In this chapter students learn about lines and angles. A line extends infinitely in both directions while an angle is formed when two lines meet at a point. Types of angles include acute right obtuse and straight. Understanding lines and angles is important for solving geometric problems and drawing shapes.