Below is screen shot of the problem. My friends book was ripped so some of the problem was cut off. Using the diagram I need to find d. The answer is supposed to be 7.42x10^4m. Below the problem is my attempt at the solution. Can someone tell me where I went wrong. As you can see from my solution my answer is slightly different. Thanks.
The Attempt at a Solution
If it is hard to tell from my scanned copy I use X' to denote the co-ordinate system that is rotated 20 degrees and I use dots above the x to denote derivatives. X double dot is acceleration and so forth.