Grazing for Mooey

A farmer tied his cow, Mooey, to a post with a rope that allowed Mooey to be a maximum of 5 m away from the post. How many square meters of grazing ground does Mooey have?

If the farmer moves Mooey to another field and ties her to a post with the same rope at the corner of a closed shed 3 m by 3 m in the field (see diagram–again, Mooey’s maximum distance from the shed is 5 m), how many square meters of grazing ground does Mooey have?

Extension
Mooey can hurt herself if she is capable of going all the way around the barn. What is the longest safe length of rope that can be tied to Mooey so she has the greatest possible grazing area? Explain.