Code หาพื้นที่วงกลม

#include <stdio.h>
float pi = 3.14;
float AreaCircle(float r) {
    return pi * r * r;
}
void main() {
    float r;
    float ans;
    printf("Enter radius : ");
    scanf("%f", &r);
    ans = AreaCircle(r);
    printf("Area = %f\n", ans);
}