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