They mark out degrees.
Degrees are a measure of angular separation, not distances. You cannot, therefore, use the protractor for determining distances.
Place the center point of the protractor at the vertex of the angle and one of the lines of the angle along the zero line of the protractor. The measure of the angle will then be where on the protractor's angular scale the other line of the angle lies.
There are no other names for protractor in English.
It is exactly halfway between the tick marks that are labelled 20 and 30.
a protractor
Protractor
The protractor may have an English sounding name, but it is not from an English speaking country. It originated in Greek in ancient times.
you might not be able to construct all the angles, but using a compass you can construct some angles by constructing angular bisectors. eg:construct angular bisector of straight line i.e; 180 degrees it gives 90 degrees
protractor
It is a protractor
It is called a protractor.
A full protractor is is a protractor that goes 360 degrees around.