#include <iostream> 
#include <cstdlib>
#include <cmath>

using namespace std;

// global constants
const double EARTH_GRAVITY = 9.8;
const double MOON_GRAVITY  = 1.67;
const double MARS_GRAVITY  = 3.71;

// function phototypes
void printOutput(string where, double h, double t, double d);
double hitDistance(double v, double a, double t);
double airTime(double v, double a, double g);
double getMaxHeight(double v, double g);
double degreesToRadians(double degrees);

int main()
{
    // variable declarations
    double v0;
    double a0;
    double height, time, distance;
    
    // get inputs
    cout << "Enter initial velocity: " ;   
    cin >> v0;
    cout << "Enter initial hit angle: " ; 
    cin >> a0;
    
    // convert angle from degree to radian
    a0 = degreesToRadians(a0);
    
    // compute & print results
    height = getMaxHeight(v0, EARTH_GRAVITY);
    time   = airTime(v0, a0, EARTH_GRAVITY);
    distance = hitDistance(v0, a0, time);
    printOutput("On Earth", height, time, distance);
      
    height = getMaxHeight(v0, MARS_GRAVITY);
    time   = airTime(v0, a0, MARS_GRAVITY);
    distance = hitDistance(v0, a0, time);
    printOutput("On Mars", height, time, distance);
    
    height = getMaxHeight(v0, MOON_GRAVITY);
    time   = airTime(v0, a0, MOON_GRAVITY);
    distance = hitDistance(v0, a0, time);
    printOutput("On the Moon", height, time, distance);
    
    system( "PAUSE");
    return 0;
}

// need to do function bodies below