"Quantitative" in math refers to quantities that can be assigned numerical values and measured; they can be expressed with specific numbers (with or without units) and used in mathematical operations.
A 20-sided polygon is a closed shape with 20 sides and 20 vertices, and the sum of its interior angles is 3240 degrees.
Qualitative data in math and statistics refers to non-numerical data that can't be used for arithmetic operations and is only meant to represent categories, attributes, or characteristics.
A degree is a unit used in geometry to measure the size of an angle, symbolized as °. A full circle is divided into 360 equal parts, and each part is defined as 1 degree.
Units of measurement are standards for measuring the size of things. The internationally used system is the International System of Units, while the commonly used system in China is the traditional Chinese system. In ancient times, it was called 'du liang heng'.
Compass-and-straightedge construction refers to the method of drawing geometric figures using only an unmarked straightedge and a compass, performing a limited number of steps. For example, drawing a line segment equal to a given one is one of its basic applications. This way of constructing shapes originated in ancient Greece and is a classic topic in plane geometry, emphasizing logical rigor and the limitations of the tools.
An equilateral triangle is a triangle where all three sides are of equal length, also called a regular triangle. It's a special kind of isosceles triangle, and all three angles are 60 degrees.
The equator is the circle on the Earth's surface with a latitude of 0°, dividing the Earth into the Southern and Northern Hemispheres, and it's also the longest line of latitude on Earth.
An arithmetic sequence is a sequence where, starting from the second term, the difference between each term and the previous one is the same constant. This fixed difference is called the common difference, usually represented by the letter d. For example, the common odd number sequence 1, 3, 5, 7... has a difference of 2 between each pair of consecutive numbers, which makes it an arithmetic sequence with a common difference of 2.