Flatland is populated by geometric shapes, ranging from isosceles trianges to equilateral triangles to squares, pentagons, hexagons, all the way up to circles.

Triangle ABC equals Triangle Aprime, Bprime, Cprime.

Geometric Right Angle Triangle

Geometric Isosceles Triangle

Let me draw it a little bit neater than that.

Triangle

triangle

So it's 1 2 ab.

Uh, it's a triangle.

So this come straight angle angle side congruency

And then we have something interesting

Push it and it becomes house shaped.

Triangle

Equilateral Triangle

You move these two triangles over here together into a single triangle. It looks like this.

We're on problem 15.

So let me draw some right triangles, let me just draw one right triangle.

Angle of the trajectory, multiplied by the square root of an isosceles triangle,

This line is a perpendicular bisector of AB, and so we have two right triangles

Three sided cells

So let's see if we can do the same with triangles.

And it deals with right triangles.

You could think of an isosceles triangle, over here.

Now, both of these triangles are also isosceles triangles, so their base angles are going to be the same. So that's one base angle, that's the other base angle.

Let me draw my right triangle just like that.

How do I know it's not 15 or 16?

A very fancy word for a very simple idea.

If you drop an altitude from the the top, or the unique angle, or the unique vertex in an isosceles triangle you will split it into two symmetric right triangles.

So we have the focal length.

And then we see that triangle AEC must be congruent to triangle DEB by side angle side

Select this Rational Bézier Cubic

Select this triangle

Remove a Triangle

Add a Triangle

Move a Triangle

Show a Triangle

Hide a Triangle

Triangular pyramid

These triangles are similar.

And how about the Bermuda Triangle? You're not going to deny... I am.

Your task in this problem is to write a regular polygon creator.

And then what you can see is both of the triangles and when I say both of the triangles

And since that is a triangle that has a 90 degree angle, it's a right triangle.

So, we now know that the triangle, I'll keep this in yellow, triangle AEB is congruent to triangle DEC by side angle side congruency, by SAS congruent triangles

Яагаад гэвэл гурвалжины нийт өнцгүүд 180 градус байдаг.