Cubic units are used to measure the volume of objects and are commonly used in everyday life to describe the space or capacity of containers.
A cube root refers to a number that, when multiplied by itself three times, equals the target number. For example, 2 cubed is 8, so 2 is the cube root of 8, written as ³√8=2. Every real number has exactly one cube root.
Cryptography is the technical science that studies how to encrypt and decrypt information. Simply put, it's about figuring out how to hide information so others can't understand it, and how to restore the hidden information.
Climate change isn't just about the weather getting hotter; it refers to long-term, statistically significant changes in temperature and weather patterns. The latest data shows that by 2025, the global average temperature has risen about 1.43°C compared to pre-industrial levels, and human activities are the main driver.
Congruence generally refers to congruent figures. Congruent figures are two flat shapes that can completely overlap each other, meaning their shapes and sizes are exactly the same. They can match up perfectly after shifting, rotating, or flipping. As a special case, congruent triangles have all corresponding sides and angles exactly equal.
Congruent means having exactly the same shape and size, while similar means having the same shape but possibly different sizes. Actually, congruence is just a special case of similarity where the ratio is 1.
Data collection, also known as data gathering, is the first step in the data processing and analysis workflow. It refers to the process of obtaining raw information from various sources using either manual or automated techniques. The sources are diverse, including databases, sensors, the internet, business systems, and public data sources, and the data collected can be either structured or unstructured. Common methods include surveys, manual entry, and automated techniques using web crawlers, API interfaces, or log systems. This process needs to follow core principles like accuracy, completeness, timeliness, consistency, and security. Data collection forms the foundation for decision-making and innovation in statistics, business intelligence, scientific research, and many other fields.
Numbers can mainly be divided into natural numbers, integers, rational numbers, irrational numbers, real numbers, and complex numbers.
Conditional probability is about how likely something is to happen given that you already know something else has happened.
Two lines a and b are cut by a third line c. The angles that are on the same side of the cutting line c and on the same side of the two lines a and b are called corresponding angles. When lines a and b are cut by a third line c, 'three lines and eight angles' appear, which include 4 pairs of corresponding angles, 2 pairs of alternate interior angles, and 2 pairs of same-side interior angles.
A convex polygon is a polygon where all the interior angles are less than 180 degrees, with no 'indentations,' and any line connecting two vertices stays inside the shape.
Calculus is a branch of advanced mathematics that studies the differentiation and integration of functions and their applications. The core is to use mathematical methods to analyze rates of change and accumulated quantities. It's based on the theory of limits and consists of two main parts: differential calculus and integral calculus.
A coefficient is the numerical factor in a term of an algebraic expression, usually showing the quantitative relationship between variables. For example, the Pearson correlation coefficient can measure how strongly variables are related.
Cosine is a type of trigonometric function in math. Simply put, in a right triangle, it's the ratio of the length of a sharp angle's adjacent side to the length of the hypotenuse.
Cosmology is a branch of astronomy that studies the overall structure, evolution, and origin of the universe. Its core content includes the standard model made up of dark energy and dark matter, and it reveals the large-scale features of the universe through observations and theory. This field combines physics, philosophy, and other areas, is based on general relativity, and relies on observational techniques like cosmic microwave background radiation and supernova redshift to test theoretical models.
A circle is a type of geometric shape, defined as the figure formed when a line segment rotates all the way around one of its fixed endpoints in a plane.
The circumference of a circle refers to the total length of the curve when it is laid out flat.
It is made up of two equal-sized, parallel circles (bases) and a curved surface (side) that connects the two bases.
A cone is a solid figure formed when the other two sides of a right triangle are rotated 360 degrees around the line of the triangle's right-angle side.
A cuboid is a prism with a rectangular base. A cube is a special kind of cuboid, a cuboid with all six faces being squares.
A cube is a solid figure made up of 6 identical squares, also called a cube or regular hexahedron.
Coordinate geometry is basically the analytic geometry everyone knows, mainly relying on setting up a coordinate system and turning geometric shapes into algebraic equations to calculate.
Coordinate axes are a set of reference lines used to determine the position of points in space. The most common ones are the horizontal axis (x-axis) and vertical axis (y-axis) in a plane Cartesian coordinate system, and they are perpendicular to each other and intersect at the origin.