Goniometer

A goniometer is an instrument that either measures an angle or allows an object to be rotated to a precise angular position, with the everyday protractor being the type most commonly used in mechanics, engineering and geometry. The term comes from the Greek words for angle and measure, and the first known description of a goniometer, built on the earlier astrolabe, was given by Gemma Frisius in 1538. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/