Answer: 45.26 ft
Explanation:
Hi, since the situation forms a right triangle (see attachment) we have to apply the next trigonometric function.
Sin α = opposite side / hypotenuse
Where α is the angle of elevation of the string to the ground, the hypotenuse is the longest side of the triangle (in this case is the length of the string), and the opposite side (x) is the height of the kite above the hand height.
Replacing with the values given:
Sin 25 = x/ 100
Solving for x
sin25 (100) =x
x= 42.26 ft
Finally, we have to add the hand height:
42.26+3 = 45.26 ft
Feel free to ask for more if needed or if you did not understand something.