In this Python tutorial, you will learn about a **Python 3 program to calculate the area of a triangle**. Apart from that, we will also explore:

- Python 3 program to find the area of a triangle with base and height
- Python 3 program to find the area of a triangle using all three sides
- Python 3 program to find the area of a triangle using the function

To understand this program, you should have basic knowledge of the following Python programming languages:

- Syntax
- Variables and operators
- Python input and output

You can calculate the area of a triangle by numerous formulas depending on the metrics you know. For example, if you know the three sides of a triangle, you can easily calculate the area of a triangle using Heron’s formula.

We will see the Python code for every scenario to calculate the area of a triangle. To understand the theory, visit Mathisfun.

**Also Read**: Sending Emails Using Python With Image And PDF Attachments.

## Python 3 Program To Find The Area Of A Triangle With Base And Height

To calculate the area of a triangle whose base and height are known, you can use this formula = (Base x Height)/2.

Here’s the Python 3 program to calculate the area:

base = input('Enter the base of the triangle:'); # Taking base input from user base = float(base); # Converting string input data to float type height = input('Enter the height of the triangle'); # Taking height input user height = float(height); # Converting string input data to float type Area = float((base * height) / 2); # Calculateing the area of the triangle using (Base * Height)/2 print('Area of triangle', Area); # Outputting the area of the triangle

**Output**:

## Python 3 Program To Calculate The Area Of A Triangle When All Three Sides Are Known

When you know all three sides of a triangle, you can calculate the area of a triangle using Heron’s formula.

First, calculate the semi-perimeter (S) by this formula – (Side 1 + Side 2 + Side 3)/2

After that, use this formula to calculate the area – √S*(S-Side1)*(S-Side2)*(S-Side3)

Here’s the Python program.

import math Side1 = float(input('Enter the first side of the triangle = ')) #First side of the triangle Side2 = float(input('Enter the second side of the triangle = ')) #Second side of the triangle Side3 = float(input('Enter the third side of the triangle = ')) #Third side of the triangle S = float(((Side1+Side2+Side3)/2)) #Calculating semi perimeter Area = float((S*(S-Side1)*(S-Side2)*(S-Side3))) #Solving Heron's expression within square root Area = math.sqrt(Area) #Calculating the square root to find the area print("Area of the triangle = ", Area) #Outputting the area of the triangle.

**Output**:

## Python 3 program to find the area of a triangle using the function

- First, we will import the math Python library to use the math.sqrt() function to calculate the square root of any number or expression.
- In this Python program, we will use Heron’s formula to calculate the area of a triangle.
- Heron’s formula = √S*(S-Side1)*(S-Side2)*(S-Side3), where S is the semi-perimeter of a triangle.
- We will define a Python function AreaTriangle(side1, side2, side3) to find the area of a triangle.

**Code**:

import math def TriangleArea(firstSide, secondSide, thirdSide): SemiPerimeter = (firstSide + secondSide + thirdSide)/2 Area = math.sqrt((SemiPerimeter*(SemiPerimeter-firstSide)*(SemiPerimeter-secondSide)*(SemiPerimeter-thirdSide))) print("Semi Perimeter of the triangle = %.2f" %SemiPerimeter); print("Area of the triangle is %0.2f" %Area) TriangleArea(3, 4, 5)

**Output**:

Semi Perimeter of the triangle = 6.00

Area of a triangle is 6.00

## Programming Exercise:

Submit your programming exercise in the comments section or mail it to [email protected]. A few lucky problem solvers will be featured on our **Facebook page** – CodeItBro – Programming Made Fun.

**1**. Write a Python program to calculate the area of a triangle when its two sides and the angle between them are known.

**2**. Make this AreaOfTriangles.py file into a Triangle Area Calculator, i.e., the program will ask users how they would like to calculate the area of a triangle.