import java.util.Scanner;

public class TwoOperations {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int tc=in.nextInt();
        for (int t = 0; t <tc ; t++) {
            double r1=in.nextDouble(),r2=in.nextDouble();
            double triArea=((r1+r2)*r1)/2.0;
            double xx=Math.sqrt(r1*r1+(r1+r2)*(r1+r2));
//            double a=Math.asin(r1/xx);
            double a=Math.toDegrees(Math.atan(r1/(r1+r2)));
            double b=180-(90+a);
            double arc1=Math.PI*r2*r2*(a/360.0);
            double g=180-2*b;
            double L=2*r1*Math.toDegrees(Math.sin(Math.toRadians(g/2.0)));
            double d=Math.sqrt(-(L/2.0)*(L/2.0)+r1*r1);
            double h = Math.sin(Math.toRadians(g)) * r1;
            double arc2=(r1*h)/2.0;
            double arc3=Math.PI*r1*r1*((90-g)/360.0);


            double ans=triArea-(arc1+arc2+arc3);
            System.out.printf("%.9f\n",ans);




        }//fortc
    }//psvm
}//class