1, the perimeter of the rectangle = (length+width) × 2; Formula: C=(a+b)×2.
2, the perimeter of the square = side length × 4; Formula: C=4a.
3. Area of rectangle = length × width; Formula: S=ab.
4. Square area = side length × side length; Formula: s = a * a
5. Area of triangle = base × height ÷ 2; Formula: S=ah÷2.
6, parallelogram area = bottom x height; Formula: S=ah.
7. Trapezoidal area = (upper bottom+lower bottom) × height ÷ 2; Formula: s = (a+b) h ÷ 2.
8. Diameter = radius × 2; D = 2r radius = diameter ÷ 2; Formula: r=d÷2.
9. The circumference of a circle = π× diameter = π× radius× 2; Formula: c = π d = 2π r.
10, area of circle = π× radius× radius.
1 1, triangle area = bottom × height ÷ 2; Formula: S=a×h÷2.
12, square area = side length × side length; Formula: s = a× a.
13, rectangular area = length × width; Formula: s = a× b.
14, the area of parallelogram = base × height; Formula: s = a× h.
15, trapezoidal area = (upper bottom+lower bottom) × height ÷ 2; Formula: S=(a+b)h÷2.
16, sum of internal angles: sum of internal angles of triangle = 180 degrees.
17, cuboid volume = length× width× height; Formula: V=abh.
18, cuboid (or cube) volume = bottom area × height; Formula: V=abh.
19, volume of cube = side length × side length × side length; Formula: V=aaa.
20, the circumference of the circle = diameter × π; Formula: l = π d = 2π r.
2 1, circular area = radius× radius× π; Formula: s = π R2.
22. Surface (side) area of the cylinder: the surface (side) area of the cylinder is equal to the perimeter of the bottom multiplied by the height; Formula: s = ch = π DH = 2π RH.
23. Surface area of cylinder: The surface area of cylinder is equal to the perimeter of bottom multiplied by height plus the area of circles at both ends; Formula: S=ch+2s=ch+2πr2.
24. Volume of cylinder: the volume of cylinder is equal to the bottom area multiplied by the height; Formula: V=Sh.
25, the volume of the cone = 1/3 bottom x product height; Formula: V= 1/3Sh.
26. Law of Fraction Addition and subtraction: Fraction and denominator are added and subtracted, only numerator is added and subtracted, and denominator remains unchanged. Fractions of different denominators are added and subtracted, first divided, then added and subtracted.
27. Multiplication of fractions: use the product of molecules as numerator and the product of denominator as denominator.
28. The law of division of fractions: dividing by a number is equal to multiplying the reciprocal of this number.