Geometry: For all kinds of objects, if we only study their shape, size and position, but not their other properties, we will get all kinds of geometry, including three-dimensional graphics and plane graphics.
Trigonometric function: Trigonometric function is one of the basic elementary functions. It takes the angle (the most commonly used radian system in mathematics, the same below) as the independent variable, and the coordinate or its ratio of the intersection point between the terminal edge of any angle and the unit circle as the dependent variable. It can also be equivalently defined as the lengths of various line segments related to the unit circle. Trigonometric function plays an important role in studying the properties of geometric shapes such as triangles and circles, and is also a basic mathematical tool for studying periodic phenomena. In mathematical analysis, trigonometric function is also defined as the solution of infinite series or specific differential equation, which allows its value to be extended to any real value or even complex value.
Probability statistics: Probability statistics calculation, also known as computational probability statistics, is an interdisciplinary, marginal and applied branch among probability theory, mathematical statistics, computational mathematics and computer science.
Algebra: Algebra is a branch of mathematics, which studies the general solutions and properties of numbers, quantities, relationships, structures and algebraic equations (groups). Elementary algebra is generally taught in middle schools, introducing the basic ideas of algebra: studying what happens when we add or multiply numbers, understanding the concept of variables and how to establish polynomials and find their roots. The research object of algebra is not only numbers, but various abstract structures. Among them, we only care about various relationships and their nature, but we don't care about the question "what is the number itself". The common types of algebraic structures are groups, rings, fields, modules, linear spaces and so on.