#include <stdio.h>
#include <math.h>
#define PI 3.14159   // Constant for π
 
int main() {
    int choice, n;
    float length, width, radius, side, base1, base2, height;
    float a, b, c, s;
    float major_axis, minor_axis;
    float area, perimeter, circumference, surface_area, volume;
 
    // Display Menu
    printf("=== Geometry Calculator ===\n");
    printf("--- 2D Shapes ---\n");
    printf("1. Rectangle (Area & Perimeter)\n");
    printf("2. Circle (Area & Circumference)\n");
    printf("3. Square (Area & Perimeter)\n");
    printf("4. Triangle (Area & Perimeter)\n");
    printf("5. Trapezium (Area)\n");
    printf("6. Parallelogram (Area & Perimeter)\n");
    printf("7. Rhombus (Area & Perimeter)\n");
    printf("8. Ellipse (Area & Approx. Perimeter)\n");
    printf("9. Regular Polygon (Area & Perimeter)\n");
 
    printf("\n--- 3D Shapes ---\n");
    printf("10. Cube (Surface Area & Volume)\n");
    printf("11. Cuboid (Surface Area & Volume)\n");
    printf("12. Sphere (Surface Area & Volume)\n");
    printf("13. Cylinder (Surface Area & Volume)\n");
    printf("14. Cone (Surface Area & Volume)\n");
 
    printf("\nEnter your choice (1-14): ");
    scanf("%d", &choice);
 
    switch(choice) {
        // 2D SHAPES
        case 1: // Rectangle
            printf("\nEnter length and width: ");
            scanf("%f %f", &length, &width);
            area = length * width;
            perimeter = 2 * (length + width);
            printf("Area = %.2f, Perimeter = %.2f\n", area, perimeter);
            break;
 
        case 2: // Circle
            printf("\nEnter radius: ");
            scanf("%f", &radius);
            area = PI * radius * radius;
            circumference = 2 * PI * radius;
            printf("Area = %.2f, Circumference = %.2f\n", area, circumference);
            break;
 
        case 3: // Square
            printf("\nEnter side: ");
            scanf("%f", &side);
            area = side * side;
            perimeter = 4 * side;
            printf("Area = %.2f, Perimeter = %.2f\n", area, perimeter);
            break;
 
        case 4: // Triangle
            printf("\nEnter sides a, b, c: ");
            scanf("%f %f %f", &a, &b, &c);
            perimeter = a + b + c;
            s = perimeter / 2;
            area = sqrt(s * (s - a) * (s - b) * (s - c));
            printf("Area = %.2f, Perimeter = %.2f\n", area, perimeter);
            break;
 
        case 5: // Trapezium
            printf("\nEnter base1, base2 and height: ");
            scanf("%f %f %f", &base1, &base2, &height);
            area = 0.5 * (base1 + base2) * height;
            printf("Area = %.2f\n", area);
            break;
 
        case 6: // Parallelogram
            printf("\nEnter base, side, and height: ");
            scanf("%f %f %f", &base1, &side, &height);
            area = base1 * height;
            perimeter = 2 * (base1 + side);
            printf("Area = %.2f, Perimeter = %.2f\n", area, perimeter);
            break;
 
        case 7: // Rhombus
            printf("\nEnter diagonals d1 and d2, and side: ");
            scanf("%f %f %f", &a, &b, &side);
            area = (a * b) / 2;
            perimeter = 4 * side;
            printf("Area = %.2f, Perimeter = %.2f\n", area, perimeter);
            break;
 
        case 8: // Ellipse
            printf("\nEnter major axis and minor axis: ");
            scanf("%f %f", &major_axis, &minor_axis);
            area = PI * major_axis * minor_axis;
            perimeter = PI * (3*(major_axis+minor_axis) - sqrt((3*major_axis+minor_axis)*(major_axis+3*minor_axis)));
            printf("Area = %.2f, Perimeter ≈ %.2f\n", area, perimeter);
            break;
 
        case 9: // Regular Polygon
            printf("\nEnter number of sides (n) and side length: ");
            scanf("%d %f", &n, &side);
            perimeter = n * side;
            area = (n * side * side) / (4 * tan(PI / n));
            printf("Area = %.2f, Perimeter = %.2f\n", area, perimeter);
            break;
 
        // 3D SHAPES
        case 10: // Cube
            printf("\nEnter side: ");
            scanf("%f", &side);
            surface_area = 6 * side * side;
            volume = side * side * side;
            printf("Surface Area = %.2f, Volume = %.2f\n", surface_area, volume);
            break;
 
        case 11: // Cuboid
            printf("\nEnter length, width, height: ");
            scanf("%f %f %f", &length, &width, &height);
            surface_area = 2 * (length*width + width*height + height*length);
            volume = length * width * height;
            printf("Surface Area = %.2f, Volume = %.2f\n", surface_area, volume);
            break;
 
        case 12: // Sphere
            printf("\nEnter radius: ");
            scanf("%f", &radius);
            surface_area = 4 * PI * radius * radius;
            volume = (4.0/3) * PI * radius * radius * radius;
            printf("Surface Area = %.2f, Volume = %.2f\n", surface_area, volume);
            break;
 
        case 13: // Cylinder
            printf("\nEnter radius and height: ");
            scanf("%f %f", &radius, &height);
            surface_area = 2 * PI * radius * (radius + height);
            volume = PI * radius * radius * height;
            printf("Surface Area = %.2f, Volume = %.2f\n", surface_area, volume);
            break;
 
        case 14: // Cone
            printf("\nEnter radius and height: ");
            scanf("%f %f", &radius, &height);
            surface_area = PI * radius * (radius + sqrt(radius*radius + height*height));
            volume = (PI * radius * radius * height) / 3;
            printf("Surface Area = %.2f, Volume = %.2f\n", surface_area, volume);
            break;
 
        default:
            printf("\nInvalid choice! Please select 1–14.\n");
    }
 
    return 0;
}