Answer:
9.95 feet
Explanation:
total surface area = area of square base + area of 4 triangular sides
area of square = (side)²
area of triangle = (base) × (height) / 2
SA = S² + 4SL/2
340 = 11² + 4(11)(L)/2
340 = 121 + 44L/2
44L/2 = 219
44L = 438
L = 9.95