In our life, circles often greet us. It is different from other graphics. The sides of rectangles and squares are straight and have two endpoints, which can be measured. The circle is a beautiful curve figure. Widely used in architectural design, such as: round flower beds, round decorations, round is easy to roll, so the wheels are round.

In the same circle, twice the radius is equal to the diameter, so the letter formula indicates that d = 2r diameter divided by 2 equals the radius, so it is expressed in letters: r=d/2. Because the distance from each point on the circular curve to the center of the circle is equal, the axle is installed on the center of the circle, and the distance from the axle to the ground is always a radius, so that the car can run smoothly.

circle

This is a geometric figure. By definition, compasses are usually used to draw circles. The diameter and radius of the inner circle of the same circle are always the same, and the circle has countless radii and diameters. A circle is a figure with axial symmetry and central symmetry. The axis of symmetry is the straight line where the diameter lies. At the same time, the circle is a "positive infinite polygon" and "infinity" is just a concept.

A circle can be regarded as a regular polygon composed of countless infinitesimal points. The more sides a polygon has, the closer its shape, perimeter and area are to a circle. So there is no real circle in the world, and the circle is actually just a conceptual figure.