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Drawing Angles




 
In these lessons, 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
How to measure angles using a protractor.
Measuring angles using a protractor (acute angles).


 
Measuring Angles with Protractors (obtuse angles).

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 draw a Reflex Angle?


 
How to Measure a Reflex Angle Using a Protractor?

You can use the Mathway widget below to practice Algebra or other math topics. Try the given examples, or type in your own problem. Then click "Answer" to check your answer.


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