Assuming that O atoms are in contact and have a radius of 1.35 , estimate the pore

Assuming that O atoms are in contact and have a radius of 1.35 Å, estimate the pore opening formed by a planar six-, eight-, ten-, and twelve-membered SiO_4/2 ring. Note that if the rings are nonplanar, pore sizes can be considerably reduced. Consider the internal size of a circle drawn inside a ring of circles.