The answer is 400 square feet (20 ft x 20 ft).

If the dinosaur was NOT on a leash, it could could hunt anywhere in the barn.

Since the dinosaur IS on a leash, it may be limited in the area it can hunt.

Since the problem said he was tied to one corner of the barn, the furthest point in the barn is to the opposite corner. Use the Pythagorean formula to calculate the distance across the barn:

(Distance across barn)^2 = 20^2 + 20^2=400 + 400 = 800

Distance across barn = √800 ≈ 28.3 ft

Since the furthest distance between any two points in the barn is only 28.3 ft and the dinosaur's leash is 50 ft, the leash is not limiting any movement in the hunting area.

Therefore the dinosaur's hunting area is the area of the barn which = 20 x 20 = 400 sq ft.

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Don