#include <stdio.h>
#define PI 3.14159 // ค่าคงที่ของ π (Pi)
 
int main() {
    float radius; // รัศมีของวงกลม
    float area;   // พื้นที่ของวงกลม
 
    printf("Enter the radius of the circle: ");
    scanf("%f", &radius);
 
    area = PI * radius * radius; // สูตรพื้นที่วงกลม
 
    // แสดงผลพื้นที่ด้วยทศนิยม 2, 3, และ 4 ตำแหน่ง
    printf("Area of the circle (2 decimal places): %.2f\n", area);
    printf("Area of the circle (3 decimal places): %.3f\n", area);
    printf("Area of the circle (4 decimal places): %.4f\n", area);
 
    return 0;
}

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