1, circumference = pi× diameter = pi× radius× 2c = π dc = 2π r.
2. The law of multiplicative association: (ab)c=a(bc).
3. Trapezoidal area = (upper bottom+lower bottom) × height ÷2 S=(a+b)h÷2.
4. The surface area of a cuboid = (length× width+length× height+width× height )× 2s = 2 (AB+AH+BH).
5. One person's speed = meeting distance ÷ meeting time-the speed of another person.
6. cuboid volume = length× width× height formula: V=abh.
7. cuboid volume = bottom area × height formula: V=abh.
8. Surface area of the cylinder: The surface area of the cylinder is equal to the perimeter of the bottom multiplied by the height plus the area of the circles at both ends. The formula is S=ch+2s=ch+2πr2.
9. The area of a circle = 2 radius × π formula: S = π R2.
10, 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.