C=2(a+b)
Square perimeter = side length ×4
C=4a
Circumference = π× diameter
C=πd
C
=2πr
The circumference of a semicircle = half of the circumference+diameter.
πr+d
Area formula: rectangular area = length × width.
S=ab
Square area = side length × side length
S=a2
Parallelogram area = base × height
S = ah
Triangle area = base × height ÷2
S=ah÷2
Trapezoidal area = (upper bottom+lower bottom) × height ÷2
S=(a+b)h÷2
Area of circle = π× square of radius
S=πr2
Transverse area of cylinder = bottom circumference × height.
S=Ch
Surface area formula: cuboid surface area = (length× width+length× height+width× height) ×2.
S=(ab+ah+bh)×2
Surface area of cube = side length × side length ×6
S=6a2
Side area of cylinder = bottom circumference x height.
S=C
h
Surface area of cylinder = side area+bottom area ×2
S=S side +2
The bottom of
Volume formula: cuboid volume = length× width× height.
V=abh
Cubic volume = side length × side length × side length
V=a3
Cylinder volume = bottom area × height
V=Sh
(Flatten the approximate cuboid to get: cylinder volume = half of lateral area × radius.
v = ch \2×r = 2πr \2×r =πr×r)
Cone volume = bottom area × height ÷3
V=Sh÷3 or 1/3Sh.
Relationship:
Fraction application problem
Quantity of unit "1" × fraction (percentage) = corresponding quantity.
Known quantity ÷ corresponding score (percentage) = quantity in "1"
Comparison Quantity ÷ Quantity in "1" = score (percentage)
Engineering problems:
Work efficiency × working hours = total workload.
Total workload ÷ working time = working efficiency
Total amount of work ÷ work efficiency = working hours
Encountered problems:
Speed sum × meeting time = distance
Sum of distance/speed = meeting time
Distance ÷ Meeting time = speed and
Standardization issues:
Single quantity × quantity = total quantity
Total ÷ single quantity = quantity
Total Quantity ÷ Quantity = Single Quantity
Proportion:
Distance on the map: actual distance = scale
Map distance = actual distance × scale
Actual distance = distance on map/scale.
Average value:
Total number ÷ Total number of copies = average value
y
direct proportion
——
=k
(affirmative)
Inverse ratio: xy=k (certain)
x