A regular tetrahedron is a closed figure surrounded by four congruent regular triangles, all of which have the same side length. It has four faces, six sides and four vertices. Regular tetrahedron is the simplest regular polyhedron. It is different from the other four regular polyhedrons, and it is the only regular polyhedron without a symmetrical center.
Regular tetrahedron is one of the five regular polyhedrons, which has four regular triangular faces, four vertices and six sides. Regular tetrahedron is different from other four regular polyhedrons. It has no center of symmetry. A regular tetrahedron has six symmetrical planes, and each plane passes through the midpoint of one of its sides and the side opposite to this side.
A regular tetrahedron can be easily obtained from the cube as long as the diagonals AB, AC and AD of three faces are drawn from a vertex A of the cube and the two points are connected. Regular tetrahedron, like general tetrahedron, can be represented by space quadrilateral and its diagonal according to Paulica-Schwartz theorem. The duality of a regular tetrahedron is itself.
Mathematics [English: Mathematics, from ancient Greece μ? θξμα(máthēma)； Often abbreviated as math or maths, it is a discipline that studies concepts such as quantity, structure, change, space and information.
Mathematics is a universal means for human beings to strictly describe and deduce the abstract structure and mode of things, and can be applied to any problem in the real world. All mathematical objects are artificially defined in essence. In this sense, mathematics belongs to formal science, not natural science. Different mathematicians and philosophers have a series of views on the exact scope and definition of mathematics.
Mathematics (hanyu pinyin: shùXué；; ; Greek: μ α θ η μ α κ; English: mathematics or maths), whose English comes from the ancient Greek word μθξμα(máthēma), has the meaning of learning, learning and science. Ancient Greek scholars regarded it as the starting point of philosophy and the "foundation of learning".
In addition, there is a narrow and technical meaning-"mathematical research". Even in its etymology, its adjective meaning is used to refer to mathematics whenever it is related to learning.