So for this you will be doing proportions. And in this case, the proportion is
![(9)/(x) =(x)/(12)](https://img.qammunity.org/2019/formulas/mathematics/college/5w6ft3qtbxxencnfv9f0kgpf11exjljru6.png)
Firstly, you'll need to cross multiply. Your equation will look like this:
![108=x^2](https://img.qammunity.org/2019/formulas/mathematics/college/5mnnmgejbtar6dzrg4564524xwlf7ftyqr.png)
Finally, square root each side and your answer will be
. However this can be simplified.
![√(108) =√(18*6)=√(9*2*3*2)=2√(3*3*3) =3*2√(3) =6√(3)](https://img.qammunity.org/2019/formulas/mathematics/college/cecfqh5zk0b5fk0cyysy2er9d8rm6dhgso.png)
In short, your answer is
![6√(3)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/9yhtwoeu5bbm4u9yv3e3w3vdxi7gcqlr5f.png)