/*
* 解题思路：
* 题意不难理解、一直求内接圆半径、知道半径长度小于0.000001为止
*/
#include#include int main( ) { int t; double x,y,r,sum; const double pi = 4.0 * atan( 1.0 ); scanf("%d",&t); while( t-- ) { scanf("%lf%lf",&x,&y); sum = 0; r = tan( atan( y/x*2 ) /2 ) * x/2; while( r >= 0.000001 ) { sum += r; x = x/y*( y-2*r ); y -= 2*r; r = tan( atan( y/x*2 ) /2 ) * x/2; } printf("%13.6lf\n",sum*2*pi); if( t ) puts(""); } return 0; }