Untitled

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    float a, b, c, p;

printf(" pls enter the first edge of triangle:");
scanf("%f", &a);
printf(" pls enter the second edge of triangle:");
scanf("%f", &b);
printf(" pls enter the third edge of triangle:");
scanf("%f", &c);

   if (a, b, c <=0){
    printf("these three numbers must be a positive number!");
   } else {
   printf("\n the perimeter of the triangle is %f", a+b+c);
   p= (a+b+c)/2;
   printf("\n the are of the triangle is %f", sqrt(p*(p-a)*(p-b)*(p-c)) );
   }
    return 0;
}