Why is the square of the speed of light equal to the reciprocal of the permeability times the dielectric constant

Why is the square of the speed of light equal to the reciprocal of the permeability times the dielectric constant

Light is an electromagnetic wave, that is, a changing electric field produces a changing magnetic field, which in turn produces a changing electric field, from which light spreads
The exact solutions of these two fields are obtained from Maxwell's equations, and finally a wave equation is obtained. One conclusion of the wave equation is that the square of the speed of light is equal to the permeability times the dielectric constant