Draw a right-angled triangle.

3 ropes are attached to the midpoints of each side, and each rope is half the length of the side it is attached to. A goat is tied to the end of the rope on the hypotenuse, and two sheep are attached to the ropes on the shorter sides. The area of the triangle is 1 acre. Find the area that the goat can reach that the sheep cannot.


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I'm not sure how hard this should be - it was written by a university professor for my Uncle who has limited mathematical knowledge but enjoys puzzles. I can't think where to start with it though. Thanks for any help.