How to express triangles

The triangle ABC is symbolized as △ABC, the side AB of the triangle ABC can be represented by the lowercase letter C of the angle C opposite to the side AB, the AC can be represented by B, the BC can be represented by A, and the three vertices are represented by capital letters A, B and C. ..

note:

(1) The three line segments are not on a straight line, and they are connected end to end in sequence.

(2) A triangle is a closed figure.

(3)△ABC is the symbol of triangle ABC, and the single △ is meaningless.

A figure surrounded by three line segments (the endpoints of every two adjacent line segments are connected) is called a triangle. For the convenience of expression, we usually use letters A, B and C to represent the three vertices of a triangle, which is called triangle ABC. A triangle has three sides, three angles and three vertices.

Draw a vertical line from the vertex of a triangle to its opposite side. The line segment between the vertex and the vertical foot is called the height of the triangle, and the opposite side is called the bottom of the triangle. Each triangle can be drawn three times as high.

Triangle classification:

By angle:

1, acute triangle: all three internal angles of the triangle are less than 90 degrees.

2. Right triangle: One of the three internal angles of the triangle is equal to 90 degrees, which can be recorded as Rt△.

3. obtuse triangle: one of the three internal angles of the triangle is greater than 90 degrees.

In a triangle, there are at least two acute angles, and the type of triangle can be directly judged according to the largest angle.

By edge:

1, equilateral triangle; An equilateral triangle is mathematically defined as a triangle with three unequal sides.

2, isosceles triangle; An isosceles triangle refers to a triangle with two equal sides, which are called the waist of the triangle.

3. equilateral triangle. An equilateral triangle (also called a regular triangle) is a triangle with three equal sides and three equal internal angles, all of which are 60 degrees. This is an acute triangle.