perimeter
The circumference refers to the length of the closed curve, usually it also refers to the circumference. The length of the perimeter is therefore equal to the sum of all edges of the graph. The circumference of the rectangle = (length + width) x 2, the perimeter of the square = any side × 4, the perimeter of the triangle = the sum of the three sides, the circle perimeter = the diameter × the pi (π) Area of the triangle, the equilateral triangle of the perimeter of the shortest; if the same area of the quadrilateral, the square to the shortest circumference; if the same area of the pentagon, the positive pentagon The shortest perimeter; if the same area of any polygon, the circumference of the circle is the shortest. The perimeter can only be used for two-dimensional graphics (flat, curved). And three-dimensional graphics (three-dimensional) such as the column, cone, anti-prism, sphere, cylinder, cone, etc. can not be expressed in the perimeter boundary size, but to use the total surface area. Total surface area = the sum of all three sides ...