measurement using Protractor
How do we measure an angle? Using a PROTRACTOR we
can measure an angle.
A protractor has one centre and a base line. It
has two scales namely, inner scale from 0° to 180° in one direction and outer scale
from 0° to 180° in the opposite direction. Why does the protractor stop with 180°?
We can rotate the protractor and measure, so 180° is enough.
Steps To Measure an angle
Step 1 Place the centre of the protractor on
the vertex of the angle and line up the base line with
Step 2 Read the measure where the other ray
crosses the protractor.
Using Protractor to draw Right Angle (90º)
Use a Protractor to draw an angle 90º.
Using Protractor to draw an Acute Angle
Use a Protractor to draw an angle 45°.
Using Protractor to draw an Obtuse Angle
Use a protractor to draw an obtuse angle 120°.
Reflex angles are bigger than 180°. Always subtract
the given angle from 360° to get the reflex angle.
Fix a line segment and let’s have another line segment , go on rotating AC to the left.
At some point, overlap and then we are back to the same as before. So angle, keep on increasing and after
some point, return to 0º.
Is this familiar? Yes, you can see this in a clock!
Adjust the hands of the clock for
the following time, note the angle made between the hour hand and the minute hand
and write the type of angle.