Circumference of the square: C=4a(a is the side length of the square)
Square: s = the square of a {square area = side length × side length}
The size of the plane figure occupied by objects is called their area. Area is the size of a plane figure, square meters, square decimeters and square centimeters, which is a recognized unit of area and can be expressed as (m? ，dm？ ，cm？ )。
Area is a quantity indicating the degree of a two-dimensional figure or shape or plane layer in a plane. A surface region is a simulation on a two-dimensional surface of a three-dimensional object. Area can be understood as the amount of material with a given thickness, which is necessary to form a shape model.
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.
A quadrilateral with four equal sides and four right angles is a square.
The two groups of squares have parallel opposite sides and equal four sides; All four angles are 90 degrees; Diagonal lines are perpendicular, bisected and equal to each other, and each diagonal line bisects a set of diagonal lines.
A group of parallelograms with equal adjacent sides and a right angle is called a square. A group of rectangles with equal adjacent sides is called a square, and a diamond with an angle of 90 is called a square. Square is a special form of rectangle and diamond.
Extended data:
First, the area of the quadrilateral.
In the 7th century AD, Brahmagupta developed a formula, which is now called Brahmagupta formula, to calculate the area of a circular quadrilateral on its side (the quadrilateral is engraved on a circle). ?
1842, German mathematicians Karl Anton Bretschneider and Karl Georg Christian von Staudt independently discovered a formula called Bretschneider formula, which can be applied to any quadrilateral area.
Second, the area and perimeter
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.