What is the area exercise of mathematics in the third grade of primary school?

The size of an object's surface-plane figure is called their area (representing the size of a two-dimensional plane figure), which makes the definition language truly reveal the essential attributes of things, which is more logical, because the "surface" is a "trace" of "length, width and height". That is, calculate its size,

1, the perimeter of the rectangle = (length+width) ×2 C=(a+b)×2.

2. The circumference of a square = side length ×4 C=4a.

3. Area of rectangle = length× width S=ab

4. Square area = side length x side length s = a.a = a.

5. Area of triangle = base × height ÷2 S=ah÷2.

6. parallelogram area = bottom x height S=ah

7. trapezoidal area = (upper bottom+lower bottom) × height ÷ 2s = (a+b) h ÷ 2.

8. Diameter = Radius× 2D = 2r Radius = Diameter ÷2 r= d÷2

9. The circumference of a circle = π× diameter = π× radius× 2c = π d = 2π r.

10, circular area = pi × radius× radius? =πr

1 1, the surface area of a cuboid = (length× width+length× height+width× height) × 2.

12, cuboid volume = length× width× height V =abh.