Each triangle has 180 degrees.

We could do this with the unit circle as well, and it would make sense.

In the Bermuda Triangle there is a parallel universe.

You view the bond in the triangle.

In particular, side DC corresponds to side BA side DC on this bottom triangle corresponds to side BA on the top triangle

Schaalsee is a lake in Germany.

OK. Can we show the video of the triangle?

I think you might see where I'm going now. Now we know two angles of a triangle.

This distance right over is 12 5 and this distance over here is also 12 5

Well, in this triangle I just drew, what is the adjacent side to this angle?

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

A love triangle has at least two blunt angles.

A love triangle has at least two blunt angles.

I know this one, and they're in a triangle, right?

That's why I like the star problem because it has all these triangles in it that might not be obvious to you the first time you look at it.

The East Asian balance of power rested on the triangle of China, Japan, and the US.

For any angle of the triangle they show the correlation of certain parties.

Now let's think about the other angle in this triangle.

So what angle in this triangle does any angle here equal that angle?

Let's use a permanent yellow marker to draw symbols on the white triangle.

We knew about a rectangle within a rectangle, we know all about that.

Because you can't have two 90 degree angles in a triangle .

Well, the ratio between corresponding sides is always the same.

Which equation could be used to find x in triangle ABC?

On the Nordic triangle there are two bottlenecks in the Finnish rail network.

You can't have two 90 degree angles in a right triangle, can you?

I do a big piece in a triangle and these are three sections from it.

If we know two angles of a triangle, what can figure out about the third?

So we do this in the most general possible way, we assume nothing about this triangle

Well, we know the angles of a triangle add up to 180, right?

This is a right triangle. So we can do a little trigonometry.

So in a 30 60 90 triangle, the side opposite to the square root of 3 over 2 is 60 degrees.

So x plus 101 ... plus 30 is equal to 180 degrees because the angles in a triangle add up to 180 degrees.

Is this angle equal to any of these three angles in this triangle?

We've derived what all the sides relative to the hypotenuse are of a 30 60 90 triangle.

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

Now I am going to use white correction liquid to draw the symbol five points star on a blue triangular shape.

They tell us that this is a 60 degree angle. This is a 90 degree angle, they do this little square thing there.

Because they all have to add up to 180.

And he said, Oh yeah, yeah! We knew about a rectangle within a rectangle, we know all about that.

Sounds like something very complex, but you will see that it simply exploring the aspect ratio of the triangle.

Well, we learned in the last presentation which of these sides is the hypotenuse?

This the side that is opposite the right angle, and simultaneously It is the most long side in a right triangle.

And you might say, OK, I'll add that to my memory bank of things to memorize. Like the angles in a triangle are equal to 180.

Right? So it turns out that if you have 60 degrees, 60 degrees, and 60 degrees that all the sides have the same lengths, or it's an equilateral triangle.