Ok. Ich habe das hier mal etwas ausführlicher gemacht.
V = 1/3 * pi * (b/(2pi))^2 * √(1 - (b/(2pi))^2)
V = 1/3 * pi * (b^2/(4pi^2)) * √(1 - (b^2/(4pi^2)))
V = (b^2/(12pi)) * √(1 - (b^2/(4pi^2)))
V = b^2 * √((1/(144pi^2)) - (b^2/(4pi^2)) * (1/(144pi^2)))
V = b^2 * √((4pi^2)/(576pi^4) - (b^2/(576pi^4)))
V = b^2 * √( (4pi^2 - b^2)/(576pi^4) )
V = b^2 * √( (4pi^2 - b^2)/(576pi^4) )
V = b^2/(24pi^2) * √(4pi^2 - b^2)
V^2 = b^4/(576pi^4) * (4pi^2 - b^2)
V^2 = b^4/(144pi^2) - b^6/(576pi^4)