Hannah, the kite and Patricia form the vertices of a right-angled triangle with the hypotenuse side the length of the string L = 60 feet and adjacent side the distance between Hannah and Patricia = d = 16 feet.
Let the angle between the string and the sand be Ф.
By trigonometric ratios,
cosФ = adjacent/hypotenuse
= d/L
= 16 feet/60 feet
= 0.2667
Ф = cos⁻¹(0.2667)
= 74.53°
≅ 74.5°
So, he angle between the string and the sand is Ф = 74.5°