Yeah, i found out that was the answer using wolfram alpha..but can anyone show me how?
http://www.wolframalpha.com/input/?i=-%289.375-%28%2856.25pi%29%2F4%29%29%3D%2828.125arcsin%28%28 1%2F7.5%29x%29%29%2B%283.75x*sqrt%281-%28%281%2F56.25%29x^2%29
How did the come up with the part in the "Result" section?