Answer:
42 feet of string
Explanation:
First, draw a diagram of the string, the height and the angle.
the length of the string is equal to the hypotenuse of the triangle
let length of the string=x
sin(θ)=opp/hyp
sin(72°)=40ft/x
x=40ft/sin(72°)
x=42.05848897ft≈42ft