In this video, let's discuss how to identify whether two given lines are parallel or not.
So we have seen various properties in the case of parallel lines.
We have seen that consecutive interior angles will be supplementary, alternate interior angles will
be equal, alternate exterior angles will be equal and corresponding angles will be equal.
All right.
Now, when a transversal intersects two lines, right.
And it's given that a pair of corresponding angles are equal, then the two lines will be parallel.
That's the contours of what we've learned before.
So, for example, you're given two lines that these two lines that it be line and line B and it's mentioned
that there is a transversal C that's intersecting and B and it's given a pair of responding angles are
equal.
C angle one is equal to angle two.
And we know that these two angles are corresponding angles.
So if angle one is equal to angle two line, it will be parallel to nine B..
Now that's one criteria.
Another criteria would be a pair of alternate angles are equal.
You can take alternating angles or alternate exterior angles.
For example, in the same case, if it was given that angle to an angle, three are equal.
We know that these two are alternating triangles.
So if angle two is equal to angle three, then definitely line it will be parallel to line be.
All right.
Now, what is another criteria that we could check if a pair of interior angles on the same side of
the transversal right or consecutive interior angles are supplementary, that means they add up to 180
degrees.
Then also we can say that these two lines are parallel.
What does that mean?
Say, for example, this angle is angle four.
If angle two plus angle four is equal to 180 degrees, then we can be sure that line and line B are
parallel.
So you don't need to check all these criteria's.
You just need to check whether any one of them is true.
If any one of them is true, all of them will be true.
And if any one of them is true, the two given lines will be parallel.