import java.util.Scanner;

public class m1192 {
    static double g=10;

    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        double v=sc.nextInt();
        double Alfa=Math.PI*sc.nextInt()/180;
        double k=Double.parseDouble(sc.next());
        double Way=0;
        while(true){
            if(v<0.01)break;
            Way+=(v*v*Math.sin(2*Alfa))/(g);
            v=v/Math.sqrt(k);
        }
        System.out.println(String.format("%.2f", Way));
    }

}