Using a protractor, we can measure and divide a circle into equal parts by angles of different sizes. A protractor has lines with numbers that represent degrees, allowing measurement of angles greater or less than 90 degrees. While setsquares can only divide a circle into three or six equal parts, a protractor provides a tool to accurately measure any angle size and thereby divide a circle into any number of equal parts.

1. ANGLES

2. Do you know how to divide a circle
into equal parts using the corners of
the setsquares?

4. Three Parts

5. Parts of different forms

6. If we make the angle larger, number of parts
decreases because the gap between the arms decreases
Look at the angles made at the centre of the circle in each
case. If we make the angle larger, does the number of
parts increase or decrease?

7. Can we make a circle into five equal parts
using a setsquare??
Using the corners of a set squares, we
cannot make such an angle at the centre.

8. We need some other method to draw and
measure angles of different sizes.
There is a device in your geometry box to
measure angles of different sizes.
It is called a protractor

9. See the lines drawn on it?
At the end of each line, we see two numbers, one
below the other.

10. How can we measure an angle using protractor.
Look at this picture.

11. DIFFERENT TYPES OF ANGLES

12. Identify the type of angle given in the picture.