Answer:
1/2 π × d + d where d is the diagonal
Step-by-step explanation:
The perimeter of a circle is π × d where d is the diameter so half of that is 1/2 π × d. But If you are going to walk around a semicircle you need to go half way around the circle and then across a diagonal to get back to where you started so the perimeter is 1/2 π × d + d.
