1 00:00:01,190 --> 00:00:04,550 Students, welcome to geometry in this video. 2 00:00:04,730 --> 00:00:08,580 Let's discuss a few basic concepts in geometry. 3 00:00:08,960 --> 00:00:11,870 We start with points to understand points. 4 00:00:12,050 --> 00:00:13,580 Let's draw a few points. 5 00:00:15,460 --> 00:00:21,610 All right, so I'm marking four points over here, you can see that they don't have linked or bread, 6 00:00:21,940 --> 00:00:23,260 but they are just dots. 7 00:00:24,520 --> 00:00:27,110 All right, but what do we use points for? 8 00:00:27,520 --> 00:00:30,100 They are used to determine and location. 9 00:00:31,450 --> 00:00:35,560 For example, let's take a rectangle and a circle over here. 10 00:00:36,010 --> 00:00:40,370 Now, this point over here is a corner of this rectangle. 11 00:00:40,690 --> 00:00:44,710 Similarly, this point over here is the center of this circle. 12 00:00:44,980 --> 00:00:50,200 So you can see that these points were used to determine some kind of a location. 13 00:00:50,650 --> 00:00:51,020 All right. 14 00:00:51,250 --> 00:00:54,870 Now, over here, we marked four points now. 15 00:00:55,180 --> 00:00:59,080 Points are denoted or colored using capital letters. 16 00:00:59,560 --> 00:01:08,840 So let me name these points over here as A, B, C and D now because we got familiar with points. 17 00:01:08,920 --> 00:01:10,900 Let's move on to line segments. 18 00:01:12,070 --> 00:01:17,600 Let's take two points, so we have point A and point B over here. 19 00:01:18,070 --> 00:01:23,830 Now let's mark a few ways in which someone could travel from A to B. 20 00:01:25,430 --> 00:01:30,950 All right, so these are four ways in which somebody could travel from A to B, another way in which 21 00:01:30,950 --> 00:01:33,650 somebody could travel from A to B is this way. 22 00:01:33,650 --> 00:01:33,970 Right. 23 00:01:34,340 --> 00:01:37,220 And this is what we call nine segment. 24 00:01:37,220 --> 00:01:45,050 Maybe an important thing to note is that it's the shortest route from A to B, and that's what we define 25 00:01:45,050 --> 00:01:48,800 a line segment now or here we have nine segment. 26 00:01:48,810 --> 00:01:55,900 Maybe it's denoted as a B with a BA on top of it and B is also the same thing. 27 00:01:56,150 --> 00:02:00,110 And in many questions you will see that AB is just denoted as a B. 28 00:02:00,830 --> 00:02:07,100 Now over here you can see that this line segment over here as two end points, right. 29 00:02:07,580 --> 00:02:11,810 Pointy end point B are in points of this line segment. 30 00:02:11,820 --> 00:02:15,230 So it does not extend beyond point and point. 31 00:02:15,230 --> 00:02:17,330 B, let's move on two lines. 32 00:02:17,330 --> 00:02:19,460 So we have seen points and line segments. 33 00:02:19,710 --> 00:02:21,920 Let's move on to what we call a line. 34 00:02:23,900 --> 00:02:31,730 Let's draw an example of a line over here, we have Nine Ebbitt now, an interesting thing to note in 35 00:02:31,730 --> 00:02:35,000 this case is that there are two arrows on both the sides. 36 00:02:35,000 --> 00:02:35,330 Right. 37 00:02:35,540 --> 00:02:36,560 What does that mean? 38 00:02:36,710 --> 00:02:41,790 It means that this extends indefinitely towards both sides. 39 00:02:41,800 --> 00:02:43,580 So I can keep drawing it like this. 40 00:02:43,860 --> 00:02:49,500 It would be the same line to a line extends indefinitely in both directions. 41 00:02:49,670 --> 00:02:52,070 That is in contrast to a line segment. 42 00:02:52,250 --> 00:02:54,890 A line does not have endpoints. 43 00:02:55,430 --> 00:02:55,940 All right. 44 00:02:56,060 --> 00:02:59,100 So that's why we have these two arrows over here. 45 00:02:59,360 --> 00:03:05,270 Now, we do not align as a B with the bar on top of it. 46 00:03:05,270 --> 00:03:07,700 And it has two arrows, right? 47 00:03:07,850 --> 00:03:12,140 Because it indicates that it extends on both directions. 48 00:03:12,920 --> 00:03:18,660 Now, an important thing about the line is that two points are enough to determine a line. 49 00:03:18,740 --> 00:03:20,300 So you just need two points. 50 00:03:20,840 --> 00:03:24,450 Now, for example, if you have point B and point Q over here. 51 00:03:25,190 --> 00:03:25,730 All right. 52 00:03:26,120 --> 00:03:33,830 So you can only draw one line through B and Q, and this is the line that can be drawn through. 53 00:03:34,170 --> 00:03:39,770 Q You can see that there is no other line that can be drawn apart from the line that we have already 54 00:03:39,770 --> 00:03:40,140 drawn. 55 00:03:40,470 --> 00:03:45,500 Now over here, another interesting point is that I have taken to other points. 56 00:03:45,500 --> 00:03:53,450 I'm taking points over here and point B over here you can see that nine P, Q and line cream is the 57 00:03:53,450 --> 00:03:58,940 same line because the line is not limited to the space between the two points. 58 00:03:59,210 --> 00:04:02,540 It extends indefinitely in both directions. 59 00:04:02,660 --> 00:04:05,050 So these two lines are the same line. 60 00:04:05,480 --> 00:04:12,710 Now we have seen that lines can be denoted with a bar on top of it with arrows on both sides like what 61 00:04:12,710 --> 00:04:13,600 we have seen over here. 62 00:04:13,850 --> 00:04:17,780 Another way in which a line can be denoted is using small letters. 63 00:04:17,960 --> 00:04:25,370 For example, you will see questions where letters like L and M are used to denote a line. 64 00:04:25,400 --> 00:04:27,380 So, for example, I have this line over here. 65 00:04:27,590 --> 00:04:29,930 I can denote it with the letter M.