# C Program to Check Whether a Triangle is Valid or Not given Sides of Triangle

• Write a C program to enter three sides of a triangle and check whether a triangle is valid or not.

Required Knowledge

• C printf and scanf functions
• If Else statement in C
• Relational Operators in C

A triangle is a valid triangle, If and only If, the sum of any two sides of a triangle is greater than the third side.

For Example, let A, B and C are three sides of a triangle. Then, A + B > C, B + C > A and C + A > B.

### C program to check whether a triangle is valid, given sides of triangle

/*
* Given three sides of a triangle, Write a c program to
* check whether it is a valid triangle or not
*/

#include <stdio.h>

int main() {
int side1, side2, side3;

/*
* Take length of three sides of triangle as input
* from user using scanf
*/
printf("Enter Length of Three Sides of a Triangle\n");
scanf("%d %d %d", &side1, &side2, &side3);

if((side1 + side2 > side3)&&(side2 + side3 > side1)
&&(side3 + side1 > side2)) {
printf("It is a Valid Triangle\n");
} else {
printf("It is an invalid Triangle");
}

return 0;
}

Output

Enter Length of Three Sides of a Triangle
10 20 20
It is a Valid Triangle

Enter Length of Three Sides of a Triangle
10 20 40
It is an invalid Triangle