About Lesson

    Understanding elementary shapes

    • The unit of measurement of an angle is degree

    • 1°= 60′

    • 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.