from math import sqrt

n = int(input())
for _ in range(n):
    t, mu, l = map(float, input().split())
    t = int(t * 100)
    mu = int(mu * 100)
    l = int(l * 1000000)
    v = (-t + sqrt(t**2 + l / (5 * mu))) * 10 * mu
    v *= 36
    v /= 1000
    v = int(v)
    v /= 100
    print(f"{v:.2f}")