#include <stdio.h>
#include <math.h>
struct area{
double a;
double b;
double c;
};
int main(void) {
struct area triangle={5,5,5};
double p=(triangle.a+triangle.b+triangle.c)/2;
double s=p*(p-triangle.a)*(p-triangle.b)*(p-triangle.c);
printf("a:%lf\nb:%lf\nc:%lf\n三角形の面積:%lf\n",triangle.
a,triangle.
b,triangle.
c,sqrt(s
)); return 0;
}
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