The circular ring is a circular figure with axial symmetry, that is, it is folded in half along the straight line with any diameter of the circular ring, and the figures on both sides can completely overlap. Therefore, a ring has countless symmetry axes, and the straight line of each diameter is its symmetry axis.

For a ring, its symmetry axis is not a straight line passing through the center of the circle like a circle, but a straight line along any diameter of the ring. This means that the symmetry axis of a ring can have any direction and the number is infinite.

In addition, the symmetry axis of a circular ring is not limited to a straight line, but may also be a curve. For example, the symmetry axis of a circular ring can be a circular curve tangent to the center of the circular ring. There are countless symmetry axes in a ring, and the symmetry axis is a straight line along any diameter of the ring, which can be a straight line or a curve.

The application of circular ring in real life;

Bearings: rings are often used as bearings in mechanical engineering, which can reduce friction and wear in mechanical movement and improve mechanical efficiency. Bearings are usually composed of two or more rings, and there is a certain gap between rings, so that mechanical parts can rotate freely in them.

2. Pipeline: Circular rings are also widely used in pipeline engineering. For example, in the transportation of oil and natural gas, as the connector of the pipeline, the circular ring can ensure the sealing and stability of the pipeline. In addition, the ring can also be used to manufacture various pipe fittings, such as elbows and tees.

3. Vehicle manufacturing: Ring also plays an important role in vehicle manufacturing. For example, the hub of a car is composed of multiple rings, which can support the weight of the car and ensure the stability of the car. In addition, the ring is also used to manufacture various vehicle parts, such as brake discs and piston rings.

4. Building structure: The circular ring is also used for building structure. For example, the pier of a bridge is usually composed of multiple rings, which can bear the weight and pressure of the bridge. In addition, the ring can also be used to manufacture various building structural fittings, such as reinforced concrete members and steel structure members.