We're going to use trigometric functions!
So we know the angle is 63° (Ф=63°)
the length of the string is 45 ft (hyp=45)
and we need to solve for height (h=?)
Using sinФ=
We can rewrite it as
sinФ=
By isolating the height (h) we can find the value
sinФ=
h= hyp(sinФ)
Then insert value of hyp, Ф and find height
h= hyp(sinФ) = 45sin63 = 40 ft
The kite is 40 ft off the ground