#!/usr/bin/env python3

from math import *
def chk(n): #returns the area of an n-polygon
    side=(X-n*x)/n/2
    return n*side*side/tan(pi/n)
for _ in range(int(input())):
    x,X=map(int,input().split())
    if x*3>=X:print(0);continue #Pahom needs at least 3 markers
    lo=3;hi=X//x
    while hi-lo>2:
        m=(hi+lo)//2
        if chk(m)>=chk(m+1):hi=m+1
        else:lo=m
    print(max(chk(i) for i in range(lo,hi+1)))