1, distance, speed and time formula: s = vtv = s ÷ t t = s ÷ v.
2. Square perimeter formula: C=4a
3. Formula of square area: S=a2
4. Rectangular perimeter formula: C=2(a+b)
5. Rectangular area formula: S=ab
Additive commutative law: A+B = B+A.
7. Additive associative law: a+b+c=a+(b+c)
8. multiplicative commutative law: ab = b a.
9. Law of multiplication and association
10, multiplication and distribution law: [a+b] c = a c+b c.
1 1, classification of angles, from small to large: acute angle, right angle, obtuse angle, right angle and rounded corner.
12, acute angle less than 90 degrees, right angle 90 degrees, obtuse angle greater than 90 degrees but less than right angle, right angle 180 degrees, fillet 360 degrees.
13. Triangles are classified by angle: acute triangle, right triangle and obtuse triangle.
14. A triangle with three acute angles is called an acute triangle. A triangle with a right angle is called a right triangle; A triangle with an obtuse angle is called an obtuse triangle.
15. Triangles are divided into equilateral triangles, isosceles triangles and equilateral triangles.
16. Draw a vertical line from the vertex of the triangle to its opposite side. The line segment between the vertex and the vertical foot is called the height of the triangle, and the opposite side is called the bottom of the triangle.
17, the counting unit of decimals is one tenth, one hundredth, one thousandth -0. 1, 0.0 1, 0.00 1-
18. Properties of decimals: Add "0" or remove "0" at the end of decimals, and the size of decimals remains unchanged.
20. 1 angle =2 right angle 1 fillet =2 angle =4 right angle.
2 1, the triangle is stable.
22. The sum of any two sides of a triangle is greater than the third side.
23. The sum of the internal angles of a triangle is 180 degrees.
24. Learn to draw corners
25, will compare the size of decimals.
26, unit conversion
Unit of length: 1 m = 10 decimeter 1 decimeter = 10cm = 1 0mm10 decimeter =
Mass unit:1k g =1000g1t =1000kg =100000g.
Currency conversion: 1 yuan = 10 minute = 100 minute = 10 minute.
Time unit: 1 hour =60 minutes =3600 seconds 1 minute =60 seconds.
1 year = 65438+ February =365 days or 366 days 1 day =24 hours.
135780 wax, 3 1 day never goes bad. Four, six, nine, one, thirty, February 28th in a normal year and February 29th in a leap year.
Area unit: 1 m2 = 100 square decimeter 1 square decimeter = 100 square centimeter 1 m2 = 10000 square centimeter.
1 ha = 1 0000m21km2 =100ha =100000m2