Drawing Angles
Construct angles with the use of compasses instead of protractors
More Geometry Lessons
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)
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
Examples:
Draw and measure
a) a 110° angle.
b) a 27° angle
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
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
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?
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