Goniometer
use a protractor to measure angles
it would be a ruler
the measure of an angle is the degrees of an angle.
The measure of the exterior angle.
the vertex of the angle
Goniometer
Not sure what an instermant is, but an appropriate instrument is a protractor.
Such a device is known as a protractor.
An Abbe refractometer is an instrument used to measure the refractive index of a liquid, by utilizing the critical angle for total reflection.
The instrument which is used to measure snowfall is called a snow gauge.
A protractor
This instrument is a balance.
The instrument you are looking for is a compass
A marine chronometer measures time. It is a very precise instrument because it can also be used to measure the longitude of the ship at sea using the time shown and the angle of the sun.
there is special instrument named "angle distribution measuring system" for the divergence angle measurement of LEDs. my email: bkk2003@163.com
the unit used to measure angle is degree. It is also measured in radians.