Write a c++ function to find surface area of sphere?

Surface area of a sphere \(= 4\pi r^{2}\); write a C++ function that takes the radius and returns this value.

#include <iostream>
using namespace std;

float surfaceArea(float r) {
    const float PI = 3.14159;
    return 4 * PI * r * r;
}

int main() {
    float radius;
    cout << "Enter radius of the sphere: ";
    cin >> radius;
    cout << "Surface area = " << surfaceArea(radius) << endl;
    return 0;
}

The function surfaceArea() receives the radius as a parameter and returns \(4\pi r^{2}\). For \(r = 7\): \(4 \times 3.14159 \times 49 \approx 615.75\) square units.

Be careful with \(\pi\): in C/C++ the expression 22/7 uses integer division and gives 3, not 3.142. Use 22.0/7 or a decimal value like 3.14159.