 In this video I'm going to talk about angle pairs formed by a transversal. So basically what these are is a list of vocabulary words that I'm going to go over. Now these angles and these pairs are created when you have a transversal that intersects two or more lines. As we can see here we have a transversal that intersects two lines and it forms eight different angles. We're going to look at the relationship of all eight of those angles. So to start off, I already gave this away, a transversal is a line that intersects two or more lines. So a line that intersects two or more lines. There we go. A line that intersects two or more lines. So in this case this line down here is our transversal, if I can spell it correctly, with an R transversal. Notice I'm abbreviating trans with a V transversal is that line right there. Alright. Now what we're going to do is we're going to look at how all these different angles, all eight of these angles relate to one another and we have these four vocabulary words to go over that. We have corresponding angles, alternate interior angles, alternate exterior angles and same side interior angles. Now these last three, they're kind of self-explanatory but this first one is not so much corresponding angles. These are the angles now, different teachers in different books will have different definitions. I like to stay less formal with them. I don't like to do formal definitions with these. I like to say that corresponding angles are angles in the same position. Okay, they're angles in the same position. Notice I'm using the angle symbol to help me out with my abbreviating. Angles in the same position. Okay, so if I look over here I want to find an example of angles that are in the same position. Now when I'm finding angle pairs, when I'm finding angle pairs, what I want to do is I want to look at the first intersection and the second intersection to find my pair of angles. So now with a pair of angles you have to always start with one. I'm going to start with angle one right there and now I'm going to find its pair. I'm going to find the corresponding angle. So if one is one of my angles, now notice that angle one is up and to the left. Angle one is up and to the left. So on this second intersection I want to do the same direction. I want to go up and to the left. Now if I do that, notice my curve is going up and I'm going to start with the cursor is sitting on angle five. So that means angle one and angle five are in fact corresponding angles. They're in the same position. Okay, now there's not just one pair of corresponding angles, there's many, many of them. So for example three and seven are corresponding angles, two and six are corresponding angles, four and eight are corresponding angles, they're all in the same position. So there's many, many angles, there's actually, since there's eight angles there are four pairs, we caught that, eight angles, four pairs, a little bit of math there. So I'm only just giving one example. This one example though should be sufficient to understand what a corresponding angle is. All right, moving on. Now we have alternate interior angles. Alternate interior. Okay, so let's go over these, alternate interior angles, we're looking for pairs of angles. Interior means inside, so if I look at all my angles, the ones on the inside are three, four, five, six. We're looking at these ones right here. Alternate, alternate means that they're going to alternate across, back and forth across the transversal. So my definition of this is angles, start with my angle symbol. You know what? Actually these are inside angles. Interior angles, so I'm actually going to start with interior, here we go. Interior, interior angles on opposite sides of the transversal, transversal, transversal, get the R in there. So interior angles on the opposite sides of the transversal, so let's look at a couple of examples. So notice here that I can only use the angles three, four, five and six, because those are the only interior ones. Okay, so if I start with angle three, right there where my cursor is at, the other one that's going to be at the other intersection and it's going to be on the opposite side of the transversal, so you go from three all the way over here to six, from three to six, three to six. Those are as one pair, angle three and angle six. That's one pair of alternate interior angles. The other pair is going to be angle four and angle five, that's going to be the other pair. And then there's only going to be two pairs, since we have four angles to look at, there's only two pairs, but again I only wrote down one example. This next one is going to be relatively simple, it's going to be almost the exact same as the last one, except for now we're talking about alternate exterior angles. Angles on the outside that are on the opposite side of the transversals, so that's exactly what I'm going to write. Angles on opposite sides of the transversal, opposite side of the transversal. So let's take a look at an example of that, so we're looking at outside angles, seven and eight down there and one and two up there, those are the outside angles, so if I want to look at exterior angles on opposite sides of the transversal, so if we start with angle one right there, if I go to the opposite side, I'm going to have angle eight right there, there's going to be the other alternate exterior angle. Angle eight and angle one are going to be one example, angle one and angle eight, that's going to be one example of alternate exterior angles. All right, last but certainly not least, same side interior angles, same side interior angles, interior angles that are on the same side of the transversal. These vocab words are really nice because they tell you exactly what they are. So we're going to start with this, interior, interior angles, interior angles on the same side, on the same side of the transversal, transversal, okay, so interior angles on the same side of the transversal, so let's look at an example, so again we're looking at interior angles again, so we're back to the three, four, five and six, but these angles are going to be on the same side, so notice four and six, that's an example of angles that are on the same side. Angle four and angle six. Alrighty, and that's it, those are my examples of a transversal, corresponding angles, alternate interior angles, alternate exterior angles and same side interior angles. In the next video that I'm going to do, I'm going to go over examples of these, of how to apply them and I'm also going to go over the abbreviations for all of them, so you need to check out that next video to know how to abbreviate all these different long, very long vocabulary words.