Answer:
6
Step-by-step explanation:
We know that the area of a circle is equal to .
A semi-circle is a half-circle, meaning that it will have half of the area of a full circle.
Therefore, a semi-circle's area is equivalent to .
Set this equation equal to 18.
Solve for r.
We then find that r = 6.
Now, we need to find the circumference. We know that the equation for the circumference of a circle is 2r. Since we only need the perimeter of half of a circle, our circumference equation will equal
r.
Plug 6 in for r.
The perimeter of the garden is equal to 6.