In this video, let's discuss what we mean with intersecting lines and parallel lines.
Let's start with intersecting lines.
All right.
So I have a line over here and I have another line over here.
You can see that these two lines, let me name them as L1 and L2.
They have a common point, which is point B over here.
Right.
So if two lines have one common point, then they are said to be intersecting lines.
So they are meeting at one common point.
Now, we is called the point of intersection of L1 and L2.
Now, this is an important thing that you need to note over here.
Two lines cannot have more than one common point.
So if you have a statement that says two lines have two common points, then that's not possible.
The only case is if both the lines are the same line.
So if I call this Lyness 11 and I call this Lyness L2, then I can say that all the points in L1 and
L2 are common.
But other than that, it's not possible for two lines to have two common points.
You can only have one common point.
All right.
Now that we have covered intersecting lines, let's move on to parallel lines now.
Let's have Rita studying on her table or here.
Now she draws two lines.
That's line A, B, and that's line KDDI.
Now, these two lines, however much you extend them, they will not intersect.
Right now, if you have two lines like this, they have not yet intersected, but if you extend them
a little bit, you will see that they will intersect.
Right.
This is the point of intersection over here of these two lines.
But if you extend A, B and C in both directions, you will see that they will never intersect.
Therefore, we say that a B is parallel to C, so these two lines are parallel.
Now, if we call this L1 and L2, we would have written 11 parallel to L2.
Now you can see that we drew these two lines on the same surface.
Right.
So a flat surface is called a plane.
Now, two lines can be called parallel.
Only if both of them are on the same plane.
You could have two lanes which will not intersect because they are not on the same plane, but in that
case we do not call them parallel lines.
Now, what's an example?
Let's have a over here and imagine KD was drawn on the ground.
OK, so Abby is on the table and Katie was drawn on the ground, will see that these two lines will
also never intersect, right.
Even if Katie was drawn like this.
I have C over here and over here.
And if this is drawn on the ground, you will see that Abby and Katie will never intersect.
But they are not on the same surface.
Therefore, we cannot call such lines parallel lines.