Circumference = π× diameter. c=πd
The circumference of a circle =π×2× radius. C = 2π r。
1, the set of points whose distance to a fixed point is equal to a fixed length is called a circle. This fixed point is called the center of the circle and is usually represented by the letter "O".
2. The straight line connecting the center of the circle and any point on the circumference is called radius, which is usually represented by the letter "R".
3. The line segment with two ends on the circumference passing through the center of the circle is called the diameter, which is usually represented by the letter "D".
What is pi?
Mathematicians try to work out the specific value of π. Mathematician Liu Hui uses the secant method, that is, the circumference of a circle inscribed with a regular polygon and circumscribed with a regular polygon approaches the circumference of a circle, and the circle approaches a 192 polygon, with a pi of about 3. 14.
The general method of cutting circle is found in middle school mathematics textbooks. But it must be noted that, to a great extent, it is only a method to calculate pi, and it seems to be a fact that pi is C=π*d, and this method is only to determine the value of π. If you think about it carefully, you will know that this is problematic, because they have not logically proved that the circumference of a circle is really proportional to the diameter. Furthermore, their concept of circumference is only intuitive and irrational.
The application of circle in life;
1. Wheels: One of the most typical applications of circles is wheels. Whether cars, bicycles or trains, their wheels are round. This is because the round wheels can roll smoothly on the plane, making the vehicle more stable and efficient.
2. Pipes and containers: The circle is also widely used in the design of pipes and containers. For example, water pipes and gas pipes are circular, because circular pipes can better withstand internal pressure and reduce the resistance of fluid in the pipes.
In addition, many containers are also round, such as buckets and cups, because round containers can better disperse internal pressure and are more stable and durable.
3. Architecture and design: The circle is also commonly used in architecture and design. For example, the domes and arches of many buildings are round, because the round structure can better disperse the pressure and stress and make the building more stable and firm. In addition, many design elements are also circular, such as buttons and knobs, because circular elements are easier to operate and master.