# PDE-Wave Equation

the wave equation, $$u_{tt} −c^2 \Delta u = 0, \quad (t > 0 ,\, u(x,0) = f(x),\, u_t(x,0) = g(x))$$ where $x \in \mathbb{R}^n,\, n \geq 2$.

In this case we can find solution n is odd first and then find solution n is even.

In the odd case, by using Euler-Poisson-Darboux(EPD) equation, we can convert odd n into the ordinary one dimensional wave equation.

My question is that, why we can not use EPD quation in even case??