Example: Calculate Missing Rhombus Diagonal and Area in C++

// Calculate Missing Rhombus Diagonal and Area
#include <iostream>
#include <cmath> // For sqrt and pow
#include <iomanip> // For setprecision
using namespace std;

int main() {
    // Step 1: Declare and initialize variables for side and one diagonal
    double side;
    double knownDiagonal;

    cout << "Enter the side length of the rhombus (a): ";
    cin >> side;
    cout << "Enter the length of one diagonal (d1): ";
    cin >> knownDiagonal;

    // Step 2: Calculate the missing diagonal
    // From the Pythagorean theorem: a^2 = (d1/2)^2 + (d2/2)^2
    // We want to find d2, so (d2/2)^2 = a^2 - (d1/2)^2
    // d2 = 2 * sqrt(a^2 - (d1/2)^2)

    // Check for valid input to prevent square root of a negative number
    if (pow(side, 2) < pow(knownDiagonal / 2, 2)) {
        cout << "Error: The given diagonal is too long for the given side length." << endl;
        cout << "A half-diagonal cannot be longer than the side." << endl;
        return 1; // Indicate an error
    }

    double halfMissingDiagonal = sqrt(pow(side, 2) - pow(knownDiagonal / 2, 2));
    double missingDiagonal = 2 * halfMissingDiagonal;

    // Step 3: Calculate the area
    double area = (knownDiagonal * missingDiagonal) / 2;

    // Step 4: Display the results
    cout << fixed << setprecision(2); // Format output to 2 decimal places
    cout << "\n--- Rhombus Properties ---" << endl;
    cout << "Given Side Length: " << side << endl;
    cout << "Given Diagonal: " << knownDiagonal << endl;
    cout << "Calculated Missing Diagonal: " << missingDiagonal << endl;
    cout << "Calculated Area: " << area << endl;

    return 0;
}