1. The length integral of the edge around a finite area is called the perimeter, and the length of a week of a graph is the perimeter of this graph. Therefore, the perimeter is equal to the sum of all the edges of the graph. Generally represented by the letter C.
2. For triangles with the same area, the equilateral triangle has the shortest circumference; If the quadrilateral with the same area is concerned, the circumference of the square is the shortest; If pentagons with the same area are used, the perimeter of regular pentagons is the shortest; If you use any polygon with the same area, the circumference of a regular circle is the shortest. Perimeter can only be used on two-dimensional figures (planes and surfaces), and three-dimensional figures (solids) such as cylinders, cones and spheres can't express their boundary size by perimeter, but by total surface area.
3. Square perimeter formula: C positive =a×4(a is the length).
4. Rectangular perimeter formula: C length =a×2+b×2(b is the width).
5. Formula of circumference: C=πd=2πr(d is diameter, r is radius, π).
6. The perimeter formula of triangle: C = a+b+c(abc is three sides of triangle).
7. Formula of sector perimeter: C = 2R+nπR÷ 180? (n= central angle) = 2R+kR(k= radian).