1. Plane geometry formula:
-area formula: rectangular area (length× width) and triangular area (bottom× height ÷2)
-perimeter formula: square perimeter (4× side length) and rectangle perimeter (2× length +2× width)
-area formula of a circle: π× radius?
2. Algebraic formula:
The formula for solving the quadratic equation in one variable: x = (-b √ (b? -4ac)) / 2a
-factorization formula: a? -B? = (a+b)(a-b)
-Pythagorean Theorem: C? = a？ +b？ (The square of the hypotenuse of a right triangle is equal to the sum of the squares of two right angles)
3. Percentage and proportion:
-Percentages are converted into decimals and fractions: Percentages ÷ 100
-proportion: a:b = c:d means ad = bc.
4. Variables and Algebra:
-Variables: Unknown quantities are represented by letters.
-Algebraic expression: An expression consisting of variables, numbers and operators.
5. Data and statistics:
-Average value: the sum of a set of data divided by the number of data.
-Median: the median of a set of data arranged from small to large.
-mode: the value that appears most frequently in a set of data.