Triangle Valid or Not based On Sides: C Program

If the three sides of a Triangle are entered through the keyboard, write a C program to check whether the Triangle is valid or not. The Triangle is valid if the sum of two sides is greater than the largest of the three sides.

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Logic To Find Valid Triangle or Not

First we find out biggest side in the 3 sides of the triangle. Next we add the other 2 sides. Now the addition of the other 2 sides must be greater than the biggest side of the Triangle, for a Triangle to be valid. If not, its not a Triangle.

Example:
If a, b and c are 3 sides of the Triangle. If c is the largest side. Then for the Triangle to be valid, (a+b) must be greater than c.
(a+b) > c
If this is true, then Triangle is valid, if not, its invalid Triangle.

Triangle Valid or Not based On Sides: C Program

Triangle Valid or Not based On Sides: C Program

#include < stdio.h >

int main()
{
    float a, b, c, flag = 0;

    printf("Enter values for a, b and c\n");
    scanf("%f%f%f", &a, &b, &c);

    if( a>b && a>c )
    {
        flag = ((b+c) > a);
    }
    else if( b>c )
    {
        flag = ((a+c) > b);
    }
    else
    {
        flag = ((a+b) > c);
    }

    if(flag)
    {
        printf("Valid Triangle\n");
    }
    else
    {
        printf("Invalid Triangle\n");
    }

    return 0;
}

Output 1:
Enter values for a, b and c
10
4
3
Invalid Triangle

Output 2:
Enter values for a, b and c
10
15
6
Valid Triangle

In above source code, variable flag stores true(1) or false(0) value.

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