Python program to calculate area, perimeter and diagonal of a rectangle has been given below. Suppose, length and breadth of a rectangle are l unit, and b unit respectively. Then area, perimeter and diagonal of that rectangle would be l * b unit^2, 2 * (l + b) unit and sqrt(l^2 + b^2) unit, respectively.

For example, if length is 7 cm and breadth is 3 cm, then area of the rectangle would be 7 * 3 = 21 cm^2 while perimeter and diagonal would be 2 * (7 + 3) = 20 cm and sqrt(7^2 + 3^2) = sqrt(58) = 7.616 cm.

The algorithm, pseudocode, and time-complexity of the program have also been covered below.

## 1. Algorithm to calculate area, perimeter and diagonal of a rectangle

1. Take the length l and the breadth b of a rectangle as inputs.

2. Compute a = l * b

3. Compute p = 2 * (l + b)

4. Compute d = sqrt(l^2 + b^2)

5. Declare the a as the area, p as the perimeter and d as the diagonal of that rectangle.

## 2. Pseudocode to calculate area, perimeter and diagonal of a rectangle

Input : Length l and breadth b of a rectangle

Output : Area A, Perimeter P and Diagonal D of the rectangle

1. Procedure areaPerimeterDiagonal(l, w):

2. A := l * b

3. P := 2 * (l + b)

4. D := sqrt(l^2 + b^2)

5. Return A, P, D

6. End Procedure

## 3. Time complexity to calculate area, perimeter and diagonal of a rectangle

Time Complexity: O(1)

## 4. Python Program & Output to calculate area, perimeter and diagonal of a rectangle

Code has been copied
# *************************************
# 	  alphabetacoder.com
# Python program to calculate the area,
# perimeter and diameter of a rectangle
# **************************************

# take input
l = float(input("Enter the length of rectangle: "))
b = float(input("Enter the breadth of rectangle: "))

# calculate area
a = l * b
# calculate perimeter
p = 2 * (l + b)
# calculate diagonal
d = (l * l + b * b) ** 0.5

# display result upto 3 decimal places
print("Area: ", round(a, 3))
print("Perimeter: ", round(p, 3))
print("Diagonal: ", round(d, 3))


Output

Enter the length of rectangle: 8

Enter the breadth of rectangle: 3.5

Area: 28.0

Perimeter: 23.0

Diagonal: 8.732