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A radio transmitter sends signals to a railway which run along a straight track. When a set of coodinate axes is used to represent this system, the transmitter is at R(1,0), and the track T is a line w/ equation 2x+y=30, where the units are kilometers.

- Points A and be are the points of T that cross the x and y axis

- The engine receives the strongest signal at C, which is the point on T closest to R.

- P(x,y) is a general point on T

My problem is this:

let s(x) represent the distance between R(1,0) and P(x,y). Show that

s(x)= sq rt (5x^2-122x+901).

Help! I don't even know where to begin. I said that point C is

(15x-15, -60x + 900). Since RP is (x-1)i + (-2x+30)j, does the 901 in the thing I'm supposed to show have to do with... oh never mind I'm REALLY confused. Please help me. Thanks!