1 00:00:00,850 --> 00:00:06,790 In this video, let's discuss what we mean with intersecting lines and parallel lines. 2 00:00:07,060 --> 00:00:08,950 Let's start with intersecting lines. 3 00:00:09,400 --> 00:00:09,840 All right. 4 00:00:10,060 --> 00:00:13,810 So I have a line over here and I have another line over here. 5 00:00:14,140 --> 00:00:19,290 You can see that these two lines, let me name them as L1 and L2. 6 00:00:19,540 --> 00:00:22,710 They have a common point, which is point B over here. 7 00:00:22,960 --> 00:00:23,300 Right. 8 00:00:24,190 --> 00:00:30,180 So if two lines have one common point, then they are said to be intersecting lines. 9 00:00:30,310 --> 00:00:32,230 So they are meeting at one common point. 10 00:00:32,560 --> 00:00:37,720 Now, we is called the point of intersection of L1 and L2. 11 00:00:37,990 --> 00:00:40,930 Now, this is an important thing that you need to note over here. 12 00:00:41,200 --> 00:00:44,710 Two lines cannot have more than one common point. 13 00:00:45,010 --> 00:00:51,360 So if you have a statement that says two lines have two common points, then that's not possible. 14 00:00:51,520 --> 00:00:54,610 The only case is if both the lines are the same line. 15 00:00:54,820 --> 00:01:02,740 So if I call this Lyness 11 and I call this Lyness L2, then I can say that all the points in L1 and 16 00:01:02,740 --> 00:01:03,790 L2 are common. 17 00:01:03,970 --> 00:01:09,110 But other than that, it's not possible for two lines to have two common points. 18 00:01:09,340 --> 00:01:11,050 You can only have one common point. 19 00:01:11,380 --> 00:01:11,790 All right. 20 00:01:11,980 --> 00:01:17,110 Now that we have covered intersecting lines, let's move on to parallel lines now. 21 00:01:17,380 --> 00:01:21,750 Let's have Rita studying on her table or here. 22 00:01:21,940 --> 00:01:23,830 Now she draws two lines. 23 00:01:24,280 --> 00:01:27,060 That's line A, B, and that's line KDDI. 24 00:01:27,370 --> 00:01:32,530 Now, these two lines, however much you extend them, they will not intersect. 25 00:01:32,530 --> 00:01:38,620 Right now, if you have two lines like this, they have not yet intersected, but if you extend them 26 00:01:38,620 --> 00:01:40,780 a little bit, you will see that they will intersect. 27 00:01:40,780 --> 00:01:41,140 Right. 28 00:01:41,390 --> 00:01:44,410 This is the point of intersection over here of these two lines. 29 00:01:44,650 --> 00:01:50,800 But if you extend A, B and C in both directions, you will see that they will never intersect. 30 00:01:51,010 --> 00:01:57,160 Therefore, we say that a B is parallel to C, so these two lines are parallel. 31 00:01:57,460 --> 00:02:02,180 Now, if we call this L1 and L2, we would have written 11 parallel to L2. 32 00:02:02,440 --> 00:02:08,070 Now you can see that we drew these two lines on the same surface. 33 00:02:08,080 --> 00:02:08,450 Right. 34 00:02:08,860 --> 00:02:12,100 So a flat surface is called a plane. 35 00:02:12,670 --> 00:02:15,620 Now, two lines can be called parallel. 36 00:02:15,850 --> 00:02:18,690 Only if both of them are on the same plane. 37 00:02:22,850 --> 00:02:28,610 You could have two lanes which will not intersect because they are not on the same plane, but in that 38 00:02:28,610 --> 00:02:30,840 case we do not call them parallel lines. 39 00:02:31,160 --> 00:02:32,710 Now, what's an example? 40 00:02:32,990 --> 00:02:37,660 Let's have a over here and imagine KD was drawn on the ground. 41 00:02:38,730 --> 00:02:44,940 OK, so Abby is on the table and Katie was drawn on the ground, will see that these two lines will 42 00:02:44,940 --> 00:02:46,560 also never intersect, right. 43 00:02:46,740 --> 00:02:48,660 Even if Katie was drawn like this. 44 00:02:49,250 --> 00:02:51,680 I have C over here and over here. 45 00:02:51,810 --> 00:02:57,330 And if this is drawn on the ground, you will see that Abby and Katie will never intersect. 46 00:02:57,510 --> 00:03:00,410 But they are not on the same surface. 47 00:03:00,420 --> 00:03:03,540 Therefore, we cannot call such lines parallel lines.