Constructing A 30° Angle (without using a set square)
How to construct a 30° angle without using a set square or protractor
What you start with
Shown above is a line of any length. You are aiming to create a new line that will make an angle of 30° to this line.
- Line segment AB, AC and CB are congruent as they are all drawn with the same compass width.
- Triangle ABC is an equilateral triangle as it has three sides of equal length.
- Angle CAB has a measure of 60 degrees because all three interior angle of an equal triangle have a measure of 60 degrees.
- Next we bisect angle CAB which will give us Angle FAB = 30 degrees. See bisecting an angle if you are unsure on this step.