This angle is definitely equal to that angle, and know that this line is parallel to this line, right?

So you could imagine an angle where the two rays in that angle form a line.

UV they both intersect line CD at the exact same angle, at this angle right here.

So just drawing that little line angle thing right there,

This angle right over here, it makes a complete line.

A line that is perpendicular to that will not only intersect the line, it will intersect it at a right angle, at a 90 degree angle.

And so if you look at this angle up here on this top line where the transversal intersects the top line, what is the corresponding angle to where the transversal intersects this bottom line?

label it DE, and lets also have line segment, FG and lets say the point where the two line segments interact is H, how could we specify this angle right over here can we call it as angle H, if we say it as angle H, it could be this angle, that angle or this angle over here it could be this angle over here.

So angle 1, if you want to look at its corresponding angle, its corresponding angle on the other parallel line, or with the transversal and the other parallel

So, we know that angle ABE must be congruent to angle CDE by alternate interior angles of a transversal intersecting parallel line

Well, in chemistry, and in organic chemistry in particular, this is called a line diagram or a line angle diagram.

The exterior angle is if you extend this line out, so if I were to draw a dotted line that extends out this bottom line.

Select a point that the first half line of the angle should go through...

Select a point that the second half line of the angle should go through...

So if I have a line and if I draw an angle that goes

let me draw with some lines if I have one line like this and I have another line like that a right angle over here actually all of these would have to be right angles it would mean that this line is completely, if this line were the ground, this line is completely upright relative to this line over here. so either these, so that is what a right angle means so now that we defined right angle

larger than 90 degrees you have an obtuse angle, and if you get all the way to 180 degrees, your angle actually forms a line.

If you think about it, when you say that this angle is congruent to this angle, you're constraining the shape of this line right here.

And if you have two lines that intersect a third line at the same angle, at the same angle. so that these are actually corresponding angles.

You would say that the corresponding angle to this one right over here is this angle right up here if you were to continue this line off a little bit this is the corresponding angle and this one is the vertical but either way angle AEB let me write this down angle sorry angle ABE let me be clear careful angle ABE is going to be congruent to angle so that's ABE is congruent to angle DCE is congruent to angle DCE

These are definitely perpendicular, at least line segments, and this would be a 90 degree angle.

You can see the orange line leaving the desert floor at about a 45 degree angle there.

So if I extended this line out like I did in the example of when I defined what an exterior angle is, this exterior angle would be 120 degrees.

And now if this is an angle x in radians, what's the length of this line right here?

Angle ABC, this angle, is the same as angle DBE.

Statement two, angle 1 is congruent to angle 2, angle 3 is congruent to angle 4.

This green angle, well it's supplementary to this angle right here, so that means it adds up to 180 degrees, and that's clear because it's on kind of the same line.

You start by teaching angles an acute angle, a right angle, an obtuse angle, a straight angle.

And this angle is congruent to angle 1, then angle 1 and angle 2 must be supplementary.

Angle DBA and angle ABC are supplementary, they add up to 180 degrees, but they are also adjacent angles, they are also adjacent, and because they are supplementary and they're adjacent, if you look at the broader angle, the angle formed from the sides they don't have in common, if you look at angle DBC, this is going to be essentially a straight line, which we can call a straight angle.

That's angle A, that's angle D.

So we could use angle, angle.

That's one angle here's another angle.

You could say that this angle right here angle AB, angle ABE

In geometry, Thales' theorem states that if A, B and C are points on a circle where the line is a diameter of the circle, then the angle ABC is a right angle.

This angle plus this angle is going to be equal to this angle.

Or this angle plus this angle plus this angle is equal to 180.

And whether you can spout out, side, angle, side, and angle, side, angle.

And then this angle and this angle.

This angle is equal to this angle.

This angle is different than that angle.

That angle is equal to this angle.

angle ACB is congruent to angle DBC

Angle 1 is congruent to angle 4.

Angle 1 is congruent to angle 3.