Answer:
the area of grass is 314 square feet
Step-by-step explanation:
The radius of the circle the goat can reach is given by the length of the rope that ties the goat to the post (10 ft)
Then the area of the circle is: 
So the area of grass is 314 square feet
The answer is a.0
Concentric means these circles would have the same center, thus, the smaller circle must be inside the bigger circle. Any tangent line to the smaller circle wont be a tangent line to the bigger circle, since that tangent line would intersect at the bigger circle at 2 points. Any tangent line to the big circle will not touch the small circle... so the answer would be 0.
it's probably 679 whole tenths
Im pretty sure it would be 10??? if you are putting it as a subtraction problem if not i would try wording it more clearly