What kind of figure is a triangle? It is three-sided, and it is a closed figure. Triangle has one characteristic. No matter what triangle you draw, there will be at least two acute angles. There are three kinds of triangles, one is acute triangle, the other is right triangle and the other is obtuse triangle. These three triangles will also have at least two acute angles. This is what a triangle looks like.

If a triangle is not sealed, is it still a triangle?

Of course not. If a triangle is not closed, it is an angle.

If it is an obtuse triangle, it may be obtuse or acute. If it is a right triangle, it may be an acute angle or a right angle. If it is an acute triangle, it can only be an acute angle.

A triangle must have an area and a perimeter, otherwise how can it be a closed figure?

If you want to divide it into acute angles, obtuse angles and right angles, you must first divide those angles.

And triangles with heights. Let's take a right triangle as an example. If we take one side of a right triangle as the base, then its height must be that the base extends upward to the highest point.

If we pinch the two corners of a right triangle together and extend outward, it will definitely become an obtuse triangle, because it is getting bigger, not smaller. An acute triangle is different. If you grab his corner and extend outward, it may become a right triangle or an obtuse triangle.

And the angle of the triangle can be expressed as follows:

(obtuse angle, right angle, acute angle, triangle will do. Draw a small corner, and then write a few corners on the side. And if you want to write like this, you should also write a few corners on the side of each corner of the triangle next to you. That's all.

Moreover, the sides of a triangle can be extended indefinitely, but only if the other two sides are also extended, otherwise it is not a triangle, and if you want to extend the sides of a triangle, the degree of the angle will definitely not change. If it changes, you will draw a right triangle, and once you extend the side, you will become an acute triangle. If it is an exam, it must be finished, so if you want to extend the side, you will definitely not change the degree of the angle.

If you want to draw a triangle, the triangle has these characteristics, so you should pay attention when drawing a triangle.

1: a triangle with at least two acute angles.

2. The triangle must be sealed.

He must have sides, and the length of the sides can be different or the same.

4: Pay attention to what triangle you want to draw. If it is a right triangle, there must be a right angle and two acute angles. If it is an acute triangle, each angle must be acute, one angle must be obtuse, and the other two angles are acute. Otherwise, it is not a triangle, and you must remember that no matter what triangle it is, it has two acute angles.

5: Triangle should also have perimeter and area.

That's what I want to share.