Draw a figure.
Draw a perpendicular from the height of the ferris wheel car to the vertical radius (where the car starts ...6 o'clock).
The vertical leg of that triangle is x = 64 cos θ as long as θ<90°
The height of the car above the ground is 64-x.
Once the car is higher than the radius, you will need to figure the function differently, but with this as a start I think you should be able to do that.

Paul M.
12/11/19
Cat E.
Thank you12/11/19