Learn about Classification of Polygons Now, let’s learn how we identify triangles and let’s learn how to name the different parts. And we want to name the parts of the triangle below. So let’s recall that a triangle is called a triangle because it’s got three angles and three sides, Tri-angle. So obviously, we know a triangle has sides which is three sides and three angles. It also has three vertex or vertices which is plural. Let’s learn how to identify them. Each of these line segments that makes up a triangle, this is called a side. This is also called a side, this is a called a side. This is an angle, this is an angle, and this is an angle. Here’s a vertex, here’s a vertex, here’s a vertex, here’s a vertex. Let’s learn how to name them. When we want to look at the sides, we label the sides based on the labels of the two vertices that are the end points. So this side is CA or AC, so we have CA or AC. This side is BA or AB and this side is CD or District Court. So there are different ways to name the sides. When we want to look at angles, there are again two different ways. I can take the simple root. Well this angle is at vertex A so this is angle A, similarly this is angle B and this is angle C. We can denote the symbol of the angle by drawing an angle like this—angle AB and C. This can also be named as angle CAB which is in order. So if we start with one corner one edge, one end point, go towards the angle and then come back to the other side. So these are two line segments that form the angle. We start with one end, the angle end and the third. So the vertex CAB is the same as angle A. Note that the center letter tells us what the angle is. Similarly, this one is angle CBA and this one is angle ACB. Here’s the interesting part. So we named it angle CAB because angle A was in the center. CBA B is in the center, angle C you see is in the center. We could also name this instead of going CAB which is starting from one vertex, the angle vertex and coming down to the other vertex. I could have gone the other way. As long as I do it in order it is allowed so I can do BAC. Instead of CBA, I could have gone ABC. And this one instead of ACB which is going this way we could have gone this way BCA. So I could have three names for each of these angles. The vertices are simple. They’re an angled AB and C.