In this article we will show you, How to write Python Program to find Area Of a Triangle, Perimeter of a Triangle and Semi Perimeter of a Triangle with example. Before we step into the program, Let see the definitions and formulas behind Perimeter and Area Of a Triangle.

### 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 of a Triangle & Perimeter of a Triangle

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

**PYTHON CODE**

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# Python Program to find 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) |

**OUTPUT**

**ANALYSIS**

Following statements will allow the User to enter the three sides of the triangle a, b, c.

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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: ')) |

Next, Calculating the Perimeter of Triangle using the formula P = a+b+c.

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# calculate the Perimeter Perimeter = a + b + c |

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

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s = (a + b + c) / 2 |

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

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

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

This 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.

**PYTHON CODE**

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# Python Program to find 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 of Traiangle = %.2f" %Perimeter); print(" The Semi Perimeter of Traiangle = %.2f" %s); print(" The Area of a Triangle is %0.2f" %Area) Area_of_Triangle(6, 7, 8) |

**OUTPUT**

**ANALYSIS**

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

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import math |

Step 2: Next, We defined the function with three arguments using def keyword. It means, 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 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

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