Edge length of NaCl unit cell is 552 pm. Then which are correct statements

For NaCl $\mathrm{a}=2{\mathrm{r}}_{\mathrm{c}}+2{\mathrm{r}}_{\mathrm{a}};\mathrm{a}=2{\mathrm{r}}_{\mathrm{c}}+2{\mathrm{r}}_{\mathrm{a}}=552\mathrm{pm}$
${\mathrm{r}}_{\mathrm{c}}+{\mathrm{r}}_{\mathrm{a}}=276\mathrm{pm},{\mathrm{r}}_{\mathrm{c}}/{\mathrm{r}}_{\mathrm{a}}=0.52;{\mathrm{r}}_{\mathrm{c}}/{\mathrm{r}}_{\mathrm{a}}=95/181$
Nearest distance between two Na⁺ ions is the
distance from body centre to edge centre is
i.e, $\sqrt{(276{)}^2+(276{)}^2}=276\sqrt{2}\mathrm{pm}.$