1, rectangular area = length× width, and the calculation formula is S=ab.

2. Square area = side length × side length, and the calculation formula is S=a×a=a2.

3. The circumference of a rectangle = (length+width) ×2, and the calculation formula C=(a+b)×2.

4. Square perimeter = side length ×4, and the calculation formula is C=4a.

5. parallelogram area = base × height, and the calculation formula is S=ah.

Common area unit of primary school mathematics:

1, square kilometers

"Square kilometer" is an area unit larger than "hectare" and is generally used to calculate a larger land area. For example, China's land area is about 9.6 million square kilometers.

2, square meters

Is the metric unit of area. It is defined as the area of a square with a side length of 1 m. In life, square meters are usually referred to as "square meters" or "squares" for short. Hongkong and Taiwan Province are called "square meters".

3. Square inch

Is the metric unit of area (SI unit), which is defined as "the area of a square with a side length of 1 decimeter". Define "the area of a square with a side length of 1 decimeter".

4, square centimeters

It is a general mathematical calculation unit and area unit. Its definition is "the area of a square with a side length of 1 cm". About the size of a thumb nail.

5. Square millimeter

Is the metric unit of area (SI unit), defined as the area of a square with a side length of1mm.. The formula is 1mm? = 0.00000 1 m2 1 mm2 = 0.00000 1 mm2。