#include <iostream>
#include <cmath>

using namespace std;

int calcdist(double ang, double vel)
{
    double pi = 3.1415926535;
    double rad = 360 / (2 * pi);
    double radang = ang / rad;
    double yvel = sin(radang) * vel;
    double xvel = cos(radang) * vel;
    double y0 = 3.2;
    double y1 = 0;
    double half = 1 / 2;
    double time = ((y0 - y1 - yvel) / pow(((1 / 2) * -9.8), half));
    double dist = xvel * time;
    return dist;
}
int main()
{
    double angle, velocity;

    cout << "Welcome to Projectile Shot Distance Calculator(Note: this program will assume the projectile is fired from a 3.2m high tank)!\n";
    cout << "The answer will be in m.\n";
    cout << "Enter the angle the projectile is fired at(in degrees): " << endl;
    cin >> angle;
    cout << "Enter the velocity the projectile is fired at(in m/s): " << endl;
    cin >> velocity;

    if(angle < 0)
    {
        cout << "Angle cannot be negative!" << endl;
        cout << "Terminating program..." << endl;
        return 0;
    }
    if(velocity < 0)
    {
        cout << "Velocity cannot be negative!" << endl;
        cout << "Terminating program..." << endl;
        return 0;
    }

    double distance = calcdist(angle, velocity);

    cout << "The projectile will have travelled " << distance << "m.\n";

    return 0;
}