#include <stdio.h>
#include <math.h>
 
double sanpen(double a, double b, double c) {
    double s = (a + b + c) / 2;
    double area = sqrt(s * (s - a) * (s - b) * (s - c));
    return area;
}
 
int main() {
    double a, b, c;
 
    printf("Enter the lengths of the three sides of the triangle (a, b, c): ");
    scanf("%lf %lf %lf", &a, &b, &c);
 
    if (a + b > c && a + c > b && b + c > a) {
        double area = sanpen(a, b, c);
        printf("The area of the triangle is: %.2f\n", area);
    } else {
        printf("The given sides do not form a valid triangle.\n");
    }
 
    return 0;
}
 

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