## How to check if a triangle is valid or not in python :

In this tutorial, we will learn how to check if a triangle is valid or not in *Python*. The program will take the *angles* as input from the user and print out one message if it is valid or not.

The basic idea is to check the *sum of all angles* that we received is equal to *180* or not. If yes, then this is a *valid,* else it is *not*.

Also, we have to check if all angles are greater than *0* or not. Because, we canâ€™t have a triangle with *0* degree angle.

So the algorithm of this program is :

- Take the angles of the triangle one by one.
- Using a
*if-else*check, find if the sum of the angles is*180*or not. Also, check if all angles are greater than*0*or not. - Based on that
*if-else*block, print one message if it is a valid triangle or not.

### Python program:

Below is the complete python program:

```
first_angle = float(input("Enter the first angle : "))
second_angle = float(input("Enter the second angle : "))
third_angle = float(input("Enter the third angle : "))
if first_angle + second_angle + third_angle == 180 and first_angle != 0 and second_angle != 0 and third_angle != 0:
print("Angles are valid for a triangle")
else:
print("Invalid angles")
```

- we are reading the user input as
*float*. *first*variables are used to store the angles for the triangle by taking the value as user input.*angle, second*angle and third_angle- The
*if*condition checks if the sum of these angles are*180*and all are not equal to*0*or not. If yes, then we are printing that the angles are*valid*. Else, we are printing that they are*invalid*.

### Sample Output:

```
Enter the first angle : 179.5
Enter the second angle : .4
Enter the third angle : .1
Angles are valid for a triangle
Enter the first angle : 90
Enter the second angle : 90
Enter the third angle : 0
Invalid angles
Enter the first angle : 90
Enter the second angle : 60
Enter the third angle : 30
Angles are valid for a triangle
```

### You might also like:

- Example of python operator module lt
- How to compare one string with integer value in python
- Python program to read all numbers from a file
- Python program to find the sum of all numbers in a file
- Python program to append a single line to the end of a file
- Difference between python append() and extend() methods of list