矩形公式的周长
在二维平面中，矩形是对边相等的图形。它有四个边，因此两个相对的边的长度相同。最长的边可以称为长度（l），最短的边可以称为宽度（b）。在一个矩形中，所有的角度都等于 90°。
矩形的属性
- 它有两对平行的边并且它们相等
- 所有的角度都是直角，即角度 = 90°
矩形的周长
周长可以定义为矩形中四个边的长度之和。在矩形中，所有四个边的长度都不像正方形一样，彼此相对的边具有相等的长度。矩形的两条对角线长度相等。
长方形的周长公式
2 × (l + b)
Where,
a is the length of the rectangle
b is the breadth of the rectangle
推导
已知矩形有 4 条边，每条边有两条相等的边，让我们将一条边的长度视为“l”，将另一边的长度视为“b”。所以会有 l, l, 和 b, b。
As per perimeter definition, sum of all sides is l + l + b + b = 2l + 2b
So take 2 common, Perimeter = 2(l + b)
Therefore, Perimeter of a rectangle is 2(l + b)
示例问题
问题1：求一个长8厘米宽12厘米的长方形的周长。
解决方案：
Given, l = 8 and b = 12 cm
So, Substitute both values in perimeter formula,
P = 2(l + b) = 2(12 + 8) = 40 cm
Therefore the perimeter of a rectangle whose length is 8 cm and breadth is 12 cm is 40 units.
问题 2：求边长为 2 厘米和 4 厘米的矩形的周长
解决方案：
Given,
l = 2 and another side b = 4 cm.
So, Substitute the both values in perimeter formula,
P = 2(l + b) = 2(2 + 4) = 12 cm
Therefore, the perimeter of a rectangle whose side is 2 cm and another side is 4 cm is 12 units
问题 3：求一个边长为 10 厘米和 20 厘米的长方形卡罗姆板的周长。
解决方案：
Given,
l = 10 and another side b = 20 cm of the carrom board.
So, Substitute the both values in perimeter formula,
P = 2(l + b) = 2(10 + 20) = 60 cm.
Therefore, the perimeter of a rectangular carrom board whose side is 10 cm and another side is 20 cm is 60 units
问题 4：求一张床边长为 100 厘米和 200 厘米的周长。
解决方案：
Given,
l = 100 and another side b = 200 cm of the bed cot.
So, Substitute the both values in perimeter formula,
P = 2(l + b) = 2(100 + 200) = 600 cm.
Therefore, the perimeter of a bed cot whose sides are 100 cm and 200 cm is 600 cm.
问题 5：求最长边为 100 厘米，最短边为 34 厘米的堆肥坑的周长。
解决方案：
Given,
Longest side = 100 cm, so length (l) will be the longest side.
So l = 100 cm.
Shortest side = 34 cm, so breadth (b) will be the shortest side.
So b = 34 cm
So, Substitute the both values in perimeter formula,
P = 2(l + b) = 2(100 + 34) = 268 cm
Therefore, the perimeter of a compost pit whose longest side is 100 cm and shortest side is 34 is 268 cm