A sextant.
A protractor is used to measure an angle.
A protractor can be used to measure an angle.
The instrument used to measure a angle is called a protractor!
To measure the altitude of the North Star (Polaris), an instrument called a sextant is commonly used. The sextant allows navigators to determine the angle between the horizon and the star, which corresponds to their latitude in the Northern Hemisphere. By measuring this angle, one can accurately ascertain their position relative to the North Star.
A protractor is used to measure an angle
A protractor.
The instrument you are looking for is a compass
the vertex of the angle
A protractor is an instrument that is used when you need to measure an angle.
Some of the devices used to measure angle are Transit, Protractor and Compass.
Goniometer
Not sure what an instermant is, but an appropriate instrument is a protractor.