The circumference of a rectangle = (length+width) ×2 C=(a+b)×2?
Circumference of a square = side length ×4 C=4a
Area of rectangle = length × width S=ab?
Area of a square = side length × side length s = a a = a?
2, triangle, parallelogram, trapezoid area formula:
Area of triangle = base × height ÷2 S=ah÷2?
Area of parallelogram = base × height S=ah?
Trapezoidal area = (upper bottom+lower bottom) × height ÷2?
S=(a+b)h÷2？
3, the circumference and area of the circle formula:
Circumference = diameter × π?
Formula: L = π d = 2π r
Area of circle = radius × radius× π?
Formula: s = π r?
4. lateral area and surface area formula of cylinder:
Transverse area of cylinder:
The side area of a cylinder is equal to the perimeter of the bottom multiplied by the height.
Formula: s = ch = π DH = 2π RH.
Surface area of cylinder:
The surface area of a cylinder is equal to the perimeter of the bottom multiplied by the height plus the area of the circles at both ends.
Formula: S=ch+2s=ch+2πr?
5. Volume formula of cylindrical cone:
Cylinder volume:
The volume of a cylinder is equal to the bottom area multiplied by the height.
Formula: V=Sh?
Volume of cone = 1/3 bottom× product height.
Formula: V= 1/3Sh?
Formula related to circle:
1, area of semicircle: s semicircle = (π r 2)/2. (r is the radius).
2. The area of the circular ring: s great circle -S small circle = π (r 2-r 2) (r is the radius of the great circle and r is the radius of the small circle).
3. Circumference: C=2πr or c = π d..(d is the diameter and r is the radius).
4. The circumference of a semicircle: d+(πd)/2 or d+π r (d is the diameter and r is the radius).
5. Sector arc length L= central angle (arc system) ×R= nπR/ 180(θ is central angle) (r is sector radius).
6. Sector area S=nπ R? /360=LR/2(L is the arc length of the sector).
7. The radius of the cone bottom surface r=nR/360(r is the radius of the bottom surface) (n is the central angle).
In the sum of infinite small sector areas, so in the last formula, the sum of small arcs is the circumference of a circle, so there is S=πr? .