Understanding elementary shapes
The unit of measurement of an angle is degree
1minute= 60 seconds
One complete rotation is 360°
The angle between the North directions and East is 90°
The protractor is an instrument used to measure angles and draw angles of required magnitude.
Acute angle – It’s measure is more than 0° and less than 90°
Obtuse angle – It’s measure is more than 90° and less than 180°
An angle equal to 2 right angles, I.e, whose measure is 280° is called a straight angle.
A reflex angle is an angle which is larger than a straight angle. It’s measure is more than 180° and less than 360°
Two lines that have only one point in common are called intersecting lines.
Two lines in the same plane they do not intersect are called parallel lines. The distance between two parallel lines is the same everywhere.