Example: Compare Triangle Areas (Heron's Formula) in C

// Compare Triangle Areas (Heron's Formula)
#include <stdio.h>
#include <math.h> // Required for sqrt()

// Function to calculate area using Heron's formula
float calculateTriangleArea(float a, float b, float c) {
    // Check for valid triangle (Triangle Inequality Theorem)
    if (a + b > c && a + c > b && b + c > a) {
        float s = (a + b + c) / 2; // Semi-perimeter
        return sqrt(s * (s - a) * (s - b) * (s - c));
    } else {
        return -1.0; // Indicate an invalid triangle
    }
}

int main() {
    float a1, b1, c1; // Sides for Triangle 1
    float a2, b2, c2; // Sides for Triangle 2
    float area1, area2;

    // Step 1: Get dimensions for Triangle 1
    printf("Enter side 1 for Triangle 1: ");
    scanf("%f", &a1);
    printf("Enter side 2 for Triangle 1: ");
    scanf("%f", &b1);
    printf("Enter side 3 for Triangle 1: ");
    scanf("%f", &c1);

    // Step 2: Get dimensions for Triangle 2
    printf("Enter side 1 for Triangle 2: ");
    scanf("%f", &a2);
    printf("Enter side 2 for Triangle 2: ");
    scanf("%f", &b2);
    printf("Enter side 3 for Triangle 2: ");
f    scanf("%f", &c2);

    // Step 3: Calculate areas using the function
    area1 = calculateTriangleArea(a1, b1, c1);
    area2 = calculateTriangleArea(a2, b2, c2);

    // Step 4: Display calculated areas and comparison
    if (area1 == -1.0) {
        printf("\nInvalid sides for Triangle 1. Cannot calculate area.\n");
    } else {
        printf("\nTriangle 1 Area: %.2f\n", area1);
    }

    if (area2 == -1.0) {
        printf("Invalid sides for Triangle 2. Cannot calculate area.\n");
    } else {
        printf("Triangle 2 Area: %.2f\n", area2);
    }

    if (area1 != -1.0 && area2 != -1.0) { // Only compare if both are valid
        if (area1 > area2) {
            printf("Triangle 1 is greater than Triangle 2.\n");
        } else if (area2 > area1) {
            printf("Triangle 2 is greater than Triangle 1.\n");
        } else {
            printf("Both triangles have equal areas.\n");
        }
    } else {
        printf("Comparison cannot be made due to invalid triangle(s).\n");
    }

    return 0;
}