Exercise 2 Page 414

Whenever we use the symbol ∠, we know that it is referring to an angle. One way to name an angle is to use the letter or number that corresponds to the vertex of the angle. In this case, it is Y or 1.

∠ Y or ∠ 1 Alternatively, we can place the letter name of the vertex between the name of points that lie on the rays creating the angle. We can do this in two ways by interchanging the names of the points. Here, we have X and Z. ∠ XYZ or ∠ ZYX