The Radio Transmitter problem. help?

**The Radio Transmitter**

In hilly areas, radio reception may be poor. Consider a situation where an FM transmitter is located at the point (−1,1) behind a hill modeled by the graph of y=x−x^2, and a radio receiver is on the opposite side of the hill. Assume that the x-axis represents ground level at the base of the hill.

- What is the closest the radio can be to the hill so that reception is unobstructed?
- Write the closest position x of the radio as a function of h if the transmitter is located at (−1,h).

i worked on this for about 2 hours and i came up with no solution...if you have any method of solving at all please feel free to share it with me :/