it
It is easy to draw an equilateral triangle without a protractor. That gives a 60 degree angle. It is then simply a matter of bisecting the 60 degree angle, using an unmarked rule and compass, to get a 30 degree angle.
You can never really be certain about the measure of an angle without using a protractor, or some similar tool. Usually, you can try to "eyeball" it, though. Just remember that a right angle is the same as an angle in a square. It is also a quarter of a whole revolution.
One way is to use a protractor. There are others
A protractor is used for measuring angles and the 3 angles in a triangle add up to 180 degrees.
it
Construct an equilateral triangle because each of its 3 exterior angles measures 120 degrees
It is easy to draw an equilateral triangle without a protractor. That gives a 60 degree angle. It is then simply a matter of bisecting the 60 degree angle, using an unmarked rule and compass, to get a 30 degree angle.
You can never really be certain about the measure of an angle without using a protractor, or some similar tool. Usually, you can try to "eyeball" it, though. Just remember that a right angle is the same as an angle in a square. It is also a quarter of a whole revolution.
by using a protractor
One way is to use a protractor. There are others
A protractor is used for measuring angles and the 3 angles in a triangle add up to 180 degrees.
By using a protractor or using trigonometry
By using a protractor we can measure an angle
A protractor is normally used to construct angles.
You would need to know the interior angle because 180-interior angle = exterior angle
Using a protractor the measure of and angle is how many degrees around it is.