/* Trajectory Calculation (15 points) 


From physics we know that the horizontal travel distance
of a projectile is given by this formula:
	
      v*cos(Q)
 d =  -------- * ( v*sin(Q)  + sqrt ( (v*sin(Q))^2 +2*g*y0) )
         g

where 
    * g:  the gravitational constant (9.80 m/s^2)
    * Q:  launch angle for the projectile
    * v:  launching velocity
    * y0: starting elevation of the projectile
    * d:  horizontal travel distance at the time of impact

Write a complete C program that reads Q, v, and y0 from the keyboard and
calculates and prints d. The angle Q must be read in degrees. 
The launch speed v must be in m/s and y0 must be in meters.
You can hardcode the gravitational constant and assume that the user will
enter correct values (i.e., no error checking is required).
        
SAMPLE RUN #1:
	
Enter launch angle Q (in degrees): 45
Enter launching velocity v (in m/s): 20
Enter starting elevation y0 (in meters above 0): 0

The horizontal travel distance before the impact is 40.8163 meters

SAMPLE RUN #2:
Enter launch angle Q (in degrees): 70
Enter launching velocity v (in m/s): 50
Enter starting elevation y0 (in meters above 0): 10

The horizontal travel distance before the impact is 167.539 meters

*/ 

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define g 9.80

int main(void)
{
	double Q, v, y0;
	
	printf("Enter launch angle Q (in degrees): ");
	scanf("%lf", &Q);
	
	Q = (Q/180.0)*M_PI; // convert to radians
	
	printf("Enter launching velocity v (in m/s): ");
	scanf("%lf", &v);
	
	printf("Enter starting elevation y0 (in meters above 0): ");
	scanf("%lf", &y0);

	double  d = (v*cos(Q))/g *(v*sin(Q) + sqrt((v*sin(Q))*(v*sin(Q)) +2*g*y0));
	
    printf("\nThe horizontal travel distance before the impact is %g meters\n\n",d);
    
    system("pause");
}