Write a C program to check whether a triangle is valid or not if angles are given using if else. How to check whether a triangle can be formed or not, if its angles are given using if else in C programming. Logic to check triangle validity if angles are given in C program.

**Example**

**Input**

Input first angle: 60 Input second angle: 30 Input third angle: 90

**Output**

The triangle is valid

## Required knowledge

Basic C programming, Relational operators, If else

## Property of a triangle

A triangle is said to be a valid triangle if and only if sum of its angles is `180 °`.

## Logic to check triangle validity if angles are given

Step by step descriptive logic to check whether a triangle can be formed or not, if angles are given.

- Input all three angles of triangle in some variable say
`angle1`,`angle2`and`angle3`. - Find sum of all three angles, store sum in some variable say
`sum = angle1 + angle2 + angle3`

. - Check
`if(sum == 180)`

then, triangle can be formed otherwise not. In addition, make sure angles are greater than 0 i.e. check condition for angles`if(angle1 > 0 && angle2 > 0 && angle3 > 0)`

.

## Program to check triangle validity when angles are given

```
/**
* C program to check whether a triangle is valid or not if angles are given
*/
#include <stdio.h>
int main()
{
int angle1, angle2, angle3, sum;
/* Input all three angles of triangle */
printf("Enter three angles of triangle: \n");
scanf("%d%d%d", &angle1, &angle2, &angle3);
/* Calculate sum of angles */
sum = angle1 + angle2 + angle3;
/*
* If sum of angles is 180 and
* angle1, angle2, angle3 is not 0 then
* triangle is valid.
*/
if(sum == 180 && angle1 > 0 && angle2 > 0 && angle3 > 0)
{
printf("Triangle is valid.");
}
else
{
printf("Triangle is not valid.");
}
return 0;
}
```

Output

Enter three angles of triangle: 30 60 90 Triangle is valid.

Happy coding 😉