Share 22 knowledge points about the area of ​​plane graphics in primary school!

Please give me 22 knowledge points about the area of ​​plane graphics in primary school!

Primary school mathematics graph calculation formula

1 Square

CPerimeter SArea aSide length

Perimeter=side length*4 {C=4a} area=side length*side length {S=a*a}

2 Cube

V: Volume a: Edge length

Surface area=edge length*edge length*6 {S table=a*a*6} Volume=edge length*edge length*edge length {V=a*a*a}

3 Rectangle

CPerimeter SArea aSide length

Perimeter=(length width)*2 {C=2(a b)} Area=length*width {S=ab}

4 Cuboid

V: Volume s: Area a: Length b: Width h: Height

(1) Surface area (length*width length*height width*height)*2 {S=2(ab ah bh)}

(2)Volume=length*width*height {V=abh}

5 Triangle

sarea abase hheight

Area=base*height÷2 {s=ah÷2}

Height of triangle=area*2÷base Triangle base=area*2÷height

6 Parallelogram

sarea abase hheight

Area=base*height {s=ah}

7 Trapezoid

sarea aupper base blower base hheight

Area=(upper bottom lower bottom)*height÷2 {s=(a b)* h÷2}

8 Round

S area C perimeter ∏ d=diameter r=radius

(1)Perimeter=diameter*∏=2*∏*radius {C=∏d=2∏r}

(2)Area=radius*radius*∏

9 Cylinder

v: volume h: height s; base area r: base radius c: base perimeter

(1)Side area=Bottom perimeter*Height (2)Surface area=Side area Bottom area*2

(3) Volume = bottom area * height (4) Volume = side area ÷ 2 * radius

10 Cone

v: Volume h: Height s; Base area r: Bottom radius

Volume=base area*height÷3

Primary School Mathematics Graph Questions

1.

① From the sentence "If the upper and lower bases of a trapezoid remain unchanged and the height increases by 2 cm, the area will increase by 32 square centimeters." From this sentence, it can be concluded that the sum of the upper and lower bases of this trapezoid is 32cm

Use the formula median line: (a b)÷2=32÷2=16

(I gave 3 examples through this sentence and found that the increase in area is the sum of the upper and lower bases of the trapezoid)

②Explanation from the sentence "If the lower base and height remain unchanged and the upper base increases by 4 cm, the area will increase by 20 cm"

(a b)h÷2 →（a 4 b）h÷2

=(ah bh)÷2 =(ah bh 4h)÷2

Through this, the area increase is: 4(h÷2) Height: 20÷4*2=10cm

③Use the formula for trapezoid area (use the median line, the median line is m): mh=16*10=160cm2

2. Multiply both sides of the equation by 10 to get: 5x 2x=140

The next step is simple:

7x=140,

x=140÷7,

x=20.

is this okay?

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