Ray refers to a straight line formed by the infinite extension of one end of a line segment. A ray has only one endpoint, so it is impossible to measure its length (it is infinitely long). In Euclidean geometry, the figure formed by a point on a straight line and its edge is called a ray, and this point is called the endpoint of the ray. For the light in geometry, we usually visually regard it as the light emitted by a flashlight.
A fillet refers to the angle (i.e. 360 degrees) formed by a ray rotating around its endpoint. Two rays with the same endpoint and different directions are two different rays. Two rays with the same endpoint and the same direction are the same ray.
There are two ways to say that the circumference is 360 degrees: one is determined by the Babylonians according to the diameter of the sun By observing the apparent diameter of the sun in the sky, the Babylonians defined a circle as 360 degrees, which is exactly 1/360 of the apparent circumference of the celestial sphere, that is, 360 suns (the suns seen by people) are arranged closely adjacent to each other. So the Babylonians stipulated.
The other is determined by the nature of 360 itself. The number 360 is adopted because it is easily divisible. 360 has 22 real factors besides 1 and itself, including 2 to 10 except 7, so many special angles are integers.
The benefits of learning mathematics
People who are good at math are relatively smart and savvy, and they can show their advantages in dealing with people. The faster you think, the more ways and ideas you have. Cambridge, majoring in financial mathematics at Carnegie Mellon University in the United States, said that studying mathematics has brought her mental exercise and made me pay more attention to the rigor of thinking in my life.
Can manage money better than others. The application of mathematics in life is everywhere. Nowadays, the society is already an information society, and mathematical knowledge is used in financial management and computers. Warren Buffett is very powerful, but Buffett's power is also based on mathematics. Buffett's decision-making process is actually the method of using subjective probability.