Answer:
Step-by-step explanation:
at the center of it's gravity
Answer:
-40/33
Step-by-step explanation:

Hope that helps and hope you get better!
Answer:
4pi + 8 km
Step-by-step explanation:
the circumference of teh circle is d*pi = 8pi. since this is a semicircle the circumference is 4pi. then the perimeter is 4pi + 8