Answer:
C
Explanation:
18's factors are 2 * 3 * 3
The two 3s can reduce the result further. sqrt (2 * 3 * 3)
square root 18 = 3*sqrt(2)
There are two sides with this length. Their total is 3sqrt(2) + 3sqrt(2) = 6√2
The perimeter is the sum of all three sides = 6 + 6√2