Answer:
Lin walked southwest, creating an obtuse triangle.
Explanation:
The triangle has sides of lengths 651 ft, 615 ft, and 910 ft.
If this were a right triangle, then the Pythagorean theorem would have to work. If tis were a right triangle, the the two shorter sides would be the legs forming the right angle.
a^2 + b^2 = c^2
615^2 + 651^2 = 378225 + 432801 = 802026
sqrt(802026) = 896
Since the calculation of the length of the hypotenuse for a right angle is 896 ft, but the actual third side is 910 feet, then this is not a right triangle. In addition, in order to accommodate a longer third side, you'd have to open up the angle a bit making it an obtuse angle. This is an obtuse triangle.
Answer: Lin walked southwest, creating an obtuse triangle.