The world in addition to the round what can do tires?
good question! The more obvious is almost become common sense, sometimes more esoteric. The People make rounds of wheels and use an important nature of the circle: Place a circle in the middle of two parallel lines so that it is tangent to the two parallel lines. You can do it: no matter how the circle of movement, it is still in the two parallel lines, and always with the two parallel lines tangent. This is the definite width property of the circle, and the curve with the similarity of the circle is called the definite curve. If the vertex A is circular, the triangle is a radius, the arc is connected to the BC point, and then the vertex B is round, and the triangle is the radius of the radius. , Do arc connection AC point, and then the vertex C is round, the triangle side length for the radius, do arc connection AB point, the curve ABC is also a fixed width curve. Circle rounds are the result of the selection of human civilization during the swell, not only because of the definite width of the circle, but also because the circle is one of the most common patterns, such as the sun, the moon, etc., is the simplest of all fixed-width curves. Round is easier to process. And the stability of the fixed width is better, even if the circle is not formal, but also to maintain a good set of wide. In addition, the circle also has an important nature, the stability of the geometric center, the center of the circle (the center of the circle) in the circle when the rotation is to maintain the same height, is always the radius of the ground up radius. Imagine using another fixed-width curve given above, and its geometric center is unstable, and it is not appropriate to move the graph up and down.
You know what the first wheel of the first car is
Rail, ah, maglev train is not the use of rail it?
