hey guys this is Mr bars and uh I'm going to talk to you guys a little about in this video about the first uh two uh sections of unit 7 which is scale factor specifically scale factor for enlargement and for reduction so here's a simple little example I got here to illustrate the idea um you have a six and a half sorry 6x4 picture of Mr Simpson here and you want to get that enlarged to 12 by 8 so um you need to find the scale factor in order to do that what do we have to multiply this picture by in order to get this enlargement um well there's a formula that we can use um and this works in any situation most you guys might be able to see what number do I have to get what number I have to multiply six by to get 12 okay you guys can probably figure that out but if you can't see it there's a formula that we can use and the formula is that the scale factor is equal to the original di or sorry the scale diagram so our scale diagram in this case is the enlargement divided by the original so what we have to figure out we have to recognize what are the corresponding sides to this diagram and again the idea of corresponding sides are what sides match up so if I'm looking at corresponding sides I'm looking at this six over here and the corresponding side for six would be 12 okay and again the corresponding side for four would be eight all right so remember that our order in order to have a scale factor everything has to remain in proportion and in order to do that uh in order to do that we need to have a scale factor for everything to be the same okay so um my scale diagram so I'll just pick a pick pick a pair of corresponding sides so let me just see um so my scale diagram I'll pick this 12 divided by six and that's going to be equal to two Okay so my scale factor is two uh as simple as that and for an enlargement you always have a scale factor greater than one so it can't be one but it'll be greater than one okay all right so let me talk about a reduction so we have a slightly more complicated example here with reduction so we start out with a with our original right here and it's reduced and we get this thing okay so you want to figure out the scale factor here so the only thing that's a little bit different about this one is that the corresponding sides might be a little bit harder to find it so my scale factor I'll call it uh SF if you remember it's equal to my scale diagram divided by my original so my originals always on the bottom in our in our fraction so I'm looking at what sides correspond so I have this little guy right here well 2.3 well oh this its corresponding side is right here so um even though this one is the orientation of its change it's sort of upside down it's still uh a scale model of it or a reduction of it so if we want to find uh the scale factor we have to find corresponding sides that both have uh values on them so if I look here this one's 4.1 and its corresponding side is 10.2 so I take my scale diagram 4.1 / by 10 two and let me see what that's equal to so I'll break it my calculator and I have 4.1 / 10.2 and that equals well it's a big decimal we write at zero decimal 4 0 1 I think most examples you'd get they probably work out a little bit better than that one but your answer is zero decimal I don't like decimals too um Z decimal that's better 4 0 1 so that guys is the idea of how to find the scale factor you will run in some more complicated examples but if you follow um this formula right here then you should be fine okayy guys any questions feel free to free to ask me in class thanks