Calculating area of a circle in c++

Question

Someone help me

Answer 1

,thanks agent smith

Answer 2

https://code.sololearn.com/cllY0b806EN9/#cpp

#include <iostream>
using namespace std;

int main() {
float rad;
float result;
const float pi = 3.14;

cout << "What is the radius? ";
cin >> rad;
cout << rad << endl;
result = pi * rad * rad;
cout << "Area = " << result << endl;
return 0;
}

::::: OUTPUT :::::

What is the radius? 10
Area = 314

What is the radius? 25
Area = 1962.5

What is the radius? 5
Area = 78.5

Answer 3

huh, it appears as though sololearn has pi

#define _USE_MATH_DEFINES
#include <cmath>

cout << M_PI;