The calculation formula of perimeter diameter is diameter = perimeter ÷ π, and diameter = perimeter ÷2÷π= perimeter ÷2π.
1. The formula for finding the circumference diameter of a known circle is: diameter = circumference÷π, π is 3. 14.
2. The formula for finding the circumference diameter of a semicircle is known: R=C/2÷π=C/2π. Because the circumference of a circle =2πr, r is the radius, the circumference of a semi-circle =πr+2r, and r is the radius. Let the circumference of a circle be c, then the circumference of a semi-circle is C÷2=C/2, so the diameter R=C/2÷π=C/2π, that is, the diameter = circumference÷2÷π = circumference÷2π.
Circumference = π× diameter, so after knowing the circumference, diameter = circumference ÷π. ? 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 the edges of the graph. The circumference of a circle = π d = 2π rd is the diameter, r is the radius, π, and the circumference of a sector = 2r+nπ r ÷ 180n = central angle = 2r+krk = radian.
The understanding of perimeter is the learning content of the first grade of compulsory education mathematics, and the learning content of perimeter in the curriculum standard actually includes three levels.
First, let students know the concept of perimeter and experience it in real life. Secondly, let students master the method and process of measuring circumference. Finally, experience and feel the application of mathematics in life.
Perimeter and area
If it is a triangle with the same area, the perimeter of an equilateral triangle is the shortest; If quadrilaterals with the same area are considered, the perimeter of a square is the shortest.
If it is a Pentagon with the same area, the circumference of a regular Pentagon is the shortest; If any polygon with the same area is considered, the circumference of a regular circle is the shortest.
Perimeter can only be used for 2D graphic planes and surfaces. Cylinders, cones, spheres and other three-dimensional graphic entities can't express their boundary size by perimeter, but should use the total surface area.