Answer:
[tex]\bold{r=\dfrac{V^2}A}[/tex]
Step-by-step explanation:
[tex]\bold{A=\dfrac{V^2}r}\\^{\cdot r}\qquad ^{\cdot r}\\\bold{Ar=V^2}\\ ^{\div A}\quad\ ^{\div A}\\\bold{r=\dfrac{V^2}A}[/tex]
