For smallest dimension d, you want

d(134-d) > 4480

0 > d^2 - 134d + 4480

9 > d^2 - 134d + 4489 (add 9 to complete the square)

9 > (d-67)^2

3 > d - 67 > -3 (the square root must be in this range)

70 > d > 64

To get the desired area, the smallest dimension must be between 64 and 70 ft.

d(134-d) > 4480

0 > d^2 - 134d + 4480

9 > d^2 - 134d + 4489 (add 9 to complete the square)

9 > (d-67)^2

3 > d - 67 > -3 (the square root must be in this range)

70 > d > 64

To get the desired area, the smallest dimension must be between 64 and 70 ft.