How to write a Python Program to find the Area, Perimeter, and Semi Perimeter of a Triangle with example. Before we step into the Python Program to find the Area Of a Triangle, Let’s see the definitions and formulas behind them.

## Python Area Of a Triangle

If we know the length of three sides of a triangle, then we can calculate the area of a triangle using Heron’s Formula.

Area of a Triangle = √(s*(s-a)*(s-b)*(s-c))

Where s = (a + b + c )/ 2 (Here s = semi perimeter and a, b, c are the three sides of a triangle)

Perimeter of a Triangle = a + b + c

## Python Program to find Area and Perimeter of a Triangle

This Python program allows the user to enter three sides of the triangle. Using those values, this Python program will calculate the Perimeter of a triangle, Semi Perimeter of a triangle, and then the Area of a Triangle.

a = float(input('Please Enter the First side of a Triangle: ')) b = float(input('Please Enter the Second side of a Triangle: ')) c = float(input('Please Enter the Third side of a Triangle: ')) # calculate the Perimeter Perimeter = a + b + c # calculate the semi-perimeter s = (a + b + c) / 2 # calculate the area Area = (s*(s-a)*(s-b)*(s-c)) ** 0.5 print("\n The Perimeter of Traiangle = %.2f" %Perimeter); print(" The Semi Perimeter of Traiangle = %.2f" %s); print(" The Area of a Triangle is %0.2f" %Area)

The first three Python statements will allow the User to enter the three sides of the triangle a, b, c. Next, Calculate the Perimeter of the Triangle using the formula P = a+b+c.

# calculate the Perimeter Perimeter = a + b + c

Next, Calculate the semi perimeter using the formula (a+b+c)/2. Although we can write semi perimeter = (Perimeter/2) we want to show the formula behind it. That is why we used the standard formula.

s = (a + b + c) / 2

Calculating the Area of a triangle using Heron’s Formula:

(s*(s-a)*(s-b)*(s-c)) ** 0.5

## Python Program to find Area of a Triangle using functions

This Python program allows the user to enter three sides of the triangle. We will pass those three values to the function arguments to calculate the area of a triangle.

# using Functions import math def Area_of_Triangle(a, b, c): # calculate the Perimeter Perimeter = a + b + c # calculate the semi-perimeter s = (a + b + c) / 2 # calculate the area Area = math.sqrt((s*(s-a)*(s-b)*(s-c))) print("\n The Perimeter = %.2f" %Perimeter); print(" The Semi Perimeter = %.2f" %s); print(" The Area is %0.2f" %Area) Area_of_Triangle(6, 7, 8)

output

```
The Perimeter = 21.00
The Semi Perimeter = 10.50
The Area is 20.33
>>> Area_of_Triangle(10, 9, 12)
The Perimeter = 31.00
The Semi Perimeter = 15.50
The Area is 44.04
>>>
```

First, We imported the math library using the following statement. This will allow us to use mathematical functions like math.sqrt function.

import math

Step 2: Next, We defined the function with three arguments using the def keyword. It means the user will enter the three sides of the triangle a, b, c.

Step 3: Calculating the Area of a triangle using Heron’s Formula: sqrt(s*(s-a)*(s-b)*(s-c)); (sqrt() is the Python mathematical function inside the math library, which is used to calculate the square root.

NOTE: Please be careful while placing the open and close brackets. It may change the entire calculation if you place it wrong