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What is the circumference of rectangle and square in Beijing Normal University?
What is the circumference of the third grade of mathematics in Beijing Normal University?

The length integral of edges around a finite area is called perimeter, and the length of a graph is the perimeter of the graph. Therefore, the perimeter is equal to the sum of all the edges of the graph.

Commonly used formula:

1, triangle (general triangle, Helen formula)

Perimeter L = A+B+C (A, b and c are the lengths of three sides of a triangle, the same below).

Area S = √[p(p-a)(p-b)(p-c)], p = (1/2)(a+b+c).

2. Rectangular

Perimeter l = 2 (a+b) (a and b are the lengths of adjacent sides of a rectangle, the same below).

Area S = ab

Step 3 square

Circumference L = 4a

Area S = a^2

4, trapezoidal

Circumference L = a+b+c+d(a: upper sole, b: lower sole, length of c and d waist, the same below).

Area S = (1/2)(a+b)h(h: height of trapezoid)

5. circle

Perimeter L = 2πr(π:π, r: radius of circle, the same below)

Area S = πr^2