Find the surface area of the pyramid

Area of the square base = (6 ft) × (6 ft) = 36 ft²

Area of each triangular face = 1/2 × (6 ft) × (5 ft) = 15 ft²

Then the surface area of the pyramid is

36 ft² + 4 × (15 ft²) = 96 ft²

so the possibilities of the measurement of the side of the triangle are either it is longest side or not the longest side

when it is the longest side

s < 25 + 35s < 60

if it is not the longest side

35 < 25 + s10 < sso 10 < s < 60so the perimeter70 < p < 130