We need to prepare a square piece of paper. A square paper is a square with four equal sides and four right angles. Then we fold the paper in half, so we can get an isosceles right triangle and a rectangle. Then we unfold the paper, and we can see that there are two rectangles and two isosceles right triangles on the paper.
2. Next, we aim the rectangle in the lower right corner at the center point, and then fold the corner in the lower right corner to the corner in the upper left corner. In this way, we get a new rectangle with its long side on the left and its short side on the right. Then we aim the corner of the upper right corner at the center point and fold the corner of the upper right corner to the lower left corner. In this way, a new isosceles right triangle is obtained, and its right angle is in the lower left corner.
3. Then we aim the corner of the upper left corner at the center point and fold the corner of the upper left corner to the corner of the lower right corner. In this way, we get a new rectangle with its long side on the right and short side on the left. Then we repeat the above steps until the triangle shape is folded.
Application of triangle;
1. Mathematical field: Triangle is an important shape in three-dimensional geometry, with three equal planes and three equal angles. In analytic geometry, calculus, linear algebra and other mathematical fields, triangles are important tools to solve various problems. For example, in analytic geometry, triangles can be used to solve the relationship between points, lines and surfaces; In calculus, triangles can be used to solve problems such as surface integral and volume fraction. In linear algebra, triangles can be used to solve eigenvalue and eigenvector problems.
2. Physical field: trigonometric functions are also widely used in the physical field. For example, in mechanics, triangles can be used to analyze the force of objects; In optics, triangles can be used to analyze reflection and refraction of light. In electromagnetism, triangles can be used to analyze the propagation of electromagnetic waves.
3. Engineering field: Triangle is also widely used in engineering field. For example, in architecture, triangles can be used to design various buildings, bridges and other structures; In mechanical engineering, triangles can be used to design various machine parts; In electronic engineering, triangles can be used to design various circuit boards.
4. Daily life: Trigonometric functions are also widely used in daily life. For example, in photography, triangle composition is a common composition technique; When packaging gifts, the triangular way can fix the gifts more firmly; When building a tent, the triangular bracket can support the tent more stably.