Math problems, Sina and compass are ancient instruments to indicate the direction. Is this correct?

No, Sina is.

Compass, also known as compass, is a feng shui detection tool and a commonly used operation tool for managing style. The compass is mainly composed of a magnetic needle in the center of a disk and a series of concentric circles, each of which represents the ancient people in China's understanding of a certain level of information in the cosmic system.

The ancients in China believed that man's gas field was controlled by the gas field of the universe, that harmony between man and the universe was auspicious, and disharmony between man and the universe was fierce. So, by experience, they put all levels of information in the universe, such as the stars in the sky, everything represented by the five actions on the earth, heavenly stems and earthly branches and so on. , all on the compass. Geomantic omen is to find the most suitable position or time for a specific person or thing through the rotation of a magnetic needle. Although the concept of "magnetic field" is not mentioned in geomantic omen, the coordination of the directions, orientations and intervals of each layer on the compass implies the law of "magnetic field".