from decimal import Decimal, ROUND_DOWN

n = int(input())
for _ in range(n):
    t, mu, l = map(Decimal, input().split())
    v = (-t + (t**2 + l / (5 * mu))**(Decimal(0.5))) * 10 * mu
    v *= Decimal(3.6)
    v = v.quantize(Decimal('.01'), rounding=ROUND_DOWN)
    print(f"{v:.2f}")