Necessary conditions for holding hands. When you don't have a deep memory of a geometric figure, you can try to summarize the main points in words, such as holding hands: four lines * * * points, every two are equal and the included angles are equal.

Equilateral triangle:

An equilateral triangle (also called an equilateral triangle) is a triangle with three equal sides and three equal internal angles, all of which are 60 degrees. This is an acute triangle. An equilateral triangle is also the most stable structure. An equilateral triangle is a special isosceles triangle, so it has all the properties of an isosceles triangle.

Definition:

An equilateral triangle (also called an equilateral triangle) is a triangle with three equal sides and three equal internal angles, all of which are 60 degrees. This is an acute triangle. An equilateral triangle is also the most stable structure. An equilateral triangle is a special isosceles triangle, so it has all the properties of an isosceles triangle.

Ruler practice:

First, you can draw a regular triangle with a ruler. The method is quite simple: first draw a line segment with any length (the length of this line segment determines the side length of an equilateral triangle), then draw a circle with the two endpoints of the line segment as the center and the line segment as the radius, and the two circles intersect at two points. At any point, draw a line segment with the two endpoints of the original line segment, so the two lines and the original line segment form a regular triangle.

2. Make a ray AC on the plane, intercept the line segment AB= the side length of an equilateral triangle on the ray AC with A as the fixed endpoint, and then keep the compass span to arc on the same side of AB with A and B as the endpoints respectively, and the intersection point D of the two arcs is the third vertex of the triangle to be made.

Nature:

1, the equilateral triangle is an acute triangle, and the internal angles of the equilateral triangle are all equal, which are all 60.

2. The median line, height line and angular bisector of each side of an equilateral triangle coincide with each other. (Three lines in one).

3. An equilateral triangle is an axisymmetric figure with three symmetry axes, and the symmetry axis is the straight line where the median line, height line or angular bisector of each side is located.

4. The center of gravity, inner heart, outer heart and vertical center of an equilateral triangle coincide at one point, which is called the center of the equilateral triangle. (four hearts in one).

5. The sum of the distances from any point to three sides in an equilateral triangle is a fixed value. (equal to its height).

6. An equilateral triangle has all the properties of an isosceles triangle. (Because an equilateral triangle is a special isosceles triangle).

7. Complex number attribute.