## Intermediate Algebra for College Students (7th Edition)

$12\sqrt5$
If a triangle has sides $a,b,c$, its perimeter is $a+b+c$. Hence here: $P=\sqrt{45}+\sqrt{80}+\sqrt{125}=\sqrt9\sqrt5+\sqrt{16}\sqrt5+\sqrt{25}\sqrt5=3\sqrt5+4\sqrt5+5\sqrt5=12\sqrt5$