1, polygon interior angle and formula
The formula of polygon interior angle sum is one of the important formulas to solve polygon related problems. According to this formula, we can know that the sum of internal angles of any polygon is equal to (n-2) 180o, where n is a positive integer. This formula can calculate the sum of external angles of any polygon without knowing the specific value of n, so the formula of internal angles of polygons has important application value in solving polygon-related problems.
2. Atomic weight
Relative atomic mass is a method to measure atomic mass, which is based on112 of carbon atom mass. The relative atomic mass of other elements can be determined by comparing the mass of carbon atoms. Relative atomic mass can be used to calculate the relative atomic mass fraction of elements, and can represent the relative size of atoms relative to atomic mass.
3、L=πd=2πr
The formula for the area of a circle is L=πd=πr? Where r is the radius of the circle. This formula shows that the area of a circle is directly proportional to the square of its diameter and inversely proportional to the square of its circumference. Because of the special shape of the circle, the area of the circle can be calculated by multiplying the square of the radius r by π. This formula has important applications in mathematics and practical applications, especially in geometry and architecture.
4、S=πr2
In junior high school mathematics, there is a very famous formula called S=πr2. This formula is the product of the square of the area and radius of a circle, that is to say, the area of a circle is equal to the product of the lateral area and the bottom area of a circle. Through this formula, we can calculate the area of a circle, which is very useful in solving some geometric problems.
5. Law of Multiplication and Distribution
The law of multiplication and distribution means that when two numbers are multiplied, they can be assigned to two different integers for multiplication, and then the two products are added. This law can make us more flexible and efficient in solving mathematical problems. For example, when we need to calculate the product of two three-digit numbers, we can use multiplication and division to simplify the calculation.
Specifically, a×b×c=(a+b)×c can represent the product of two three-digit numbers, while (a+b)×c represents the multiplication and addition of these two numbers. Multiplication and distribution law is widely used, which can be used not only to solve simple multiplication problems, but also to deal with more complicated mathematical problems. Through this rule, we can allocate two numbers more efficiently and calculate their products, so as to get a more accurate result.