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The radius is 100 since their distance apart = radius = 100 ft. The distance of 60 ft represents the perpendicular length from the fence to any of the centers. So we can confirm each circle illuminates 80 * 2 = 160 ft of the fence using the 60 - 80 - 100 triangle. Finally, we need to subtract the overlap from the two fences. Note however the overlap cannot be more than 80, so the total fence length must be at least 160 + 160 - 80 = 240. We can only choose A.

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see highlighted part ; option B is 240
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The radius is 100 since their distance apart = radius = 100 ft. The distance of 60 ft represents the perpendicular length from the fence to any of the centers. So we can confirm each circle illuminates 80 * 2 = 160 ft of the fence using the 60 - 80 - 100 triangle. Finally, we need to subtract the overlap from the two fences. Note however the overlap cannot be more than 80, so the total fence length must be at least 160 + 160 - 80 = 240. We can only choose A.

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At least 240 means answer can be 240 or 260?? So A or B possible
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The radius is 100 since their distance apart = radius = 100 ft. The distance of 60 ft represents the perpendicular length from the fence to any of the centers. So we can confirm each circle illuminates 80 * 2 = 160 ft of the fence using the 60 - 80 - 100 triangle. Finally, we need to subtract the overlap from the two fences. Note however the overlap cannot be more than 80, so the total fence length must be at least 160 + 160 - 80 = 240. We can only choose A.

Attachment:
2cir.png
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see highlighted part ; option B is 240
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Only possibility exists is A, since B would mean one circle passing through point of intersection of perpendicular from fence(chord) to center of other circle(L1 or L2). This would gravely deform the diagram.

On the other side, if you are good at drawing circles to scale, you can observe that in the 60 - 80 - 100 triangle for L1 the perimeter of circle with center L2 bisects the side 80 in roughly a ratio of 1:3.

Thus the common part of fence ~ \(\frac{3}{4} * 80 = 60\).
Trying to quote 'Ron' :)

Hence A.
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Thank you for pointing that out, I have fixed my wording. The intent was to avoid doing any other calculations by seeing the overlap is certainly less than 80, so the fence length > 240.

Archit3110
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The radius is 100 since their distance apart = radius = 100 ft. The distance of 60 ft represents the perpendicular length from the fence to any of the centers. So we can confirm each circle illuminates 80 * 2 = 160 ft of the fence using the 60 - 80 - 100 triangle. Finally, we need to subtract the overlap from the two fences. Note however the overlap cannot be more than 80, so the total fence length must be at least 160 + 160 - 80 = 240. We can only choose A.

Attachment:
2cir.png
TestPrepUnlimited
see highlighted part ; option B is 240
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The length of the fence covered by the light is: S = 80+100+80=260 feet.

Answer is (A)

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Please help me understand the question
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