Module 7: Trigonometry 7.1: Angle Measure In this module we will begin looking at ideas in the realm of trigonometry. Trigonometry is grounded in thinking about angles and their measures. In this investigation we will explore angles and think about how to measure them. What is an Angle? First, we say that a ray is a geometric object with a single endpoint that extends infinitely far in one direction. An example of a ray is given below. A point is highlighted with an arrow (or ray) extending away from the point. The point is labeled as the endpoint. An angle is formed from two rays that share a common endpoint. We call this common endpoint the angle's vertex. An example is given