Lines and Angles | Class 6 Mathematics Notes

2.5 Angle

An angle is formed when two rays share a common starting point called the vertex. The rays are called the arms or sides of the angle. For example, rays arrow BD and arrow BE form an angle with vertex B. Angles are named using three points, with the vertex point in the middle, such as angle DBE or angle EBD. The size of an angle is the amount of rotation or turn needed to move one arm onto the other about the vertex. Angles can be observed in everyday life, such as the opening of a book cover, the blades of scissors, or the arms of a compass. The size of the angle increases as the amount of rotation increases.

📊 Diagram: See figure_14 to figure_20: Cases 1 to 6 showing book cover opening; figure_20: Fig. 2.8 showing angle formed by rays BD and BE; figure_21: Fig. 2.9 showing angle notation with a small curve at vertex.

🧪 Activity: Observe and identify angles in everyday objects like scissors, compasses, and spectacles.

🔗 Connection: Leads to comparing angles and measuring angles using tools.