We call this an obtuse angle.

So he's saying that angle A and angle B are both obtuse.

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

Well, clearly, in this case, angle H right here, this is an obtuse angle.

It says a triangle has, at most, one obtuse angle.

Well, obtuse just means that they have two angles, one obtuse angle might look like that where that is greater than 90 degrees there, and the other obtuse might be super obtuse.

It's a joint of tubes. You start by teaching angles an acute angle, a right angle, an obtuse angle, a straight angle.

He began by assuming, that in triangle ABC, angle A and B are both obtuse.

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.

That's what obtuse means.

You're not that obtuse.

Obtuse barracuda, Sphyraena obtusata Cuvier, 1829.

Triangle FGI must be an obtuse triangle.

So HlG would be an obtuse triangle.

Which triangles must be similar? Two obtuse triangles.

A new angle, old angle, this angle, that angle.

The leaves are smaller, long, with an obtuse (blunt pointed or rounded) apex.

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 small angle is called a glancing angle or grazing angle.

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

That's one angle here's another angle.

Is this statement true, that angle one equals 4, angle 2 equals 5, angle three equals angle 6?

Perhaps I am being obtuse and do not understand the finer points of this exercise.

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.

Incident angle is equal to reflected 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 1 is congruent to angle 4.

That's angle 1 and that's angle 2.

The only way that this would be equal to 180, angle 3 plus angle 4, is if angle 4 were a 90 degree angle, and angle 3 were also a 90 degree angle.

So this angle, this red angle and this brown angle have to be supplements.

Angle

Angle

angle

angle

Angle

Let's see, angle X congruent to angle Y.

Or angle 1 is congruent to angle 2.

This angle, this whole angle is 180 degrees.

And angle A is congruent to angle D.

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