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

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

3. (Key) The circumference of a circle = π× diameter = 2×π× radius.

4. quadrilateral: C=a+b+c+d(abcd is the side length of quadrilateral).

5. Special rectangle: C=2(a+b)(a is long and b is wide).

6. Polygon: C= sum of all sides.

The length integral of the edge around a finite area is called the perimeter, which is the length of a graph. The perimeter of a polygon is also equal to the sum of all sides of a graph, the perimeter of a circle =πd=2πr(d is the diameter, R is the radius, π), and the perimeter of a sector =2R+nπR÷ 180? (n= central angle) = 2R+kR(k= radian).

The length integral of the edge around a finite area is called the perimeter, which is the length of a graph. The perimeter is represented by the letter C. If it is a triangle with the same area, the perimeter of an equilateral triangle is the shortest. If it is a quadrilateral with the same area, the perimeter of the square is the shortest; If pentagons with the same area are used, the perimeter of a regular pentagon is the shortest.

Perimeter unit

The unit of perimeter is the unit of length, including: meter (m), millimeter (mm), centimeter (cm), decimeter (dm), kilometer (km), meter (m), micron (micron), nanometer (nm) and so on. ?

The length integral of the edge around a finite area is called the perimeter, which is the length of a graph. The perimeter of a polygon is also equal to the sum of all sides of a graph, the perimeter of a circle =πd=2πr(d is the diameter, R is the radius, π), and the perimeter of a sector =2R+nπR÷ 180? (n= central angle) =2R+kR(k= radian).