Answer:
[tex] r = \frac{12\sin 20\degree}{ \sin 35\degree } [/tex]
Step-by-step explanation:
By sine rule
[tex] \frac{r}{ \sin \angle R } = \frac{p}{ \sin \angle P} \\ \\ \frac{r}{ \sin 20\degree } = \frac{12}{ \sin 35\degree } \\ \\ r = \frac{12\sin 20\degree}{ \sin 35\degree } [/tex]
