[问答题]
A pi meson of rest mass u.iao7yq,(pm f(;u;3t(lkxy p ty c;ffed)( s96ojhsk e70 vc$m_\pi$ decays at rest into a muon (rest mass $m_\mu$) and a neutrino of negligible or zero rest mass. Show that the kinetic energy of the muon is $KE_\mu = \frac{(m_\pi - m_\mu)^2 c^2}{2m_\pi}$.
