Drawing Angles



In this lesson, we will look at how to use a protractor to

  • draw an angle less than 180˚
  • draw an angle greater than 180˚ (reflex angle)

Related Topics:
Construct angles with the use of compasses instead of protractors

More Geometry Lessons

Drawing Angles Using a Protractor

How to draw an angle less than 180˚

Example:

Draw an angle ABC, which is 55˚.

Step 1: Draw a line BC and mark B as the vertex.

 

 

Step 2: Place the centre of the protractor at the vertex B and adjust the base line to be aligned to BC.

Step 3: Find 55˚ on the outer scale of the protractor and mark that point as point A.

Step 4: Remove the protractor and draw a line from point B to point A

 

Step 5: Label and ABC





The following video will show you how to draw and measure angles using a protractor.

Measuring Angles (part 1)
How to measure angles using a protractor



Draw and measure angles using a protractor



How to draw an angle greater than 180˚ (reflex angle)

To draw a reflex angle (i.e. angle greater than 180º and less than 360º), we need to

  • Subtract the reflex angle from 360º. 
  • Draw the resulting angle as described above.
  • Mark the required angle which is outside the one that has been drawn.

Example:

Draw an angle ABC = 250˚

To draw the reflex angle, 250˚, we first draw the angle obtained by subtracting 250˚ from 360˚ which is 360˚ – 250˚ = 110˚

Step 1: Draw the line BC

line

Step 2: Place the centre of the protractor at the vertex B and adjust the base line to be aligned to BC.

Step 3: Find the angle 110˚ on the protractor (inner) scale and mark that as point A.



Step 4: Remove the protractor and draw a line from point B to point A.

Step 5: Label the reflex angle ABC





The following video will show you how to use a protractor to draw acute angles, right angles, obtuse angles and reflex angles.



How to Measure a Reflex Angle Using a Protractor ?





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