calculate volume of cone (c++)

// Calculate volume of a cone
#include <iostream>
#include <string>
#include <math.h>

float radius = 1.5;
float height = 10;

int main()
{
  float radius_S = pow(radius, 2);
  std::string radius_S_string = std::to_string(radius_S);
  std::cout << ("Radius^2: " + radius_S_string);
  float radius_StH = radius_S * height;
  std::cout << ("\nRadius^2*height: " + std::to_string(radius_StH));
  float radius_StHtP = radius_StH * M_PI;
  float radius_StHtPdOT = radius_StHtP * 1/3;
  std::cout << ("\nVolume: " + std::to_string(radius_StHtPdOT));
}