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**calculuskid1** Consider the line y=t(x + 1), where t is rational, and passing through two points on the unit circle (around the origin O): the point P (−1, 0) and the point R(x, y), say in the first quadrant. Consider the two angles given by RP and RO with the x-axis. Call them ψ and θ, respectively. Show that ψ = θ/2.

So what I tried doing was subbing in t(x + 1)=y inso x^2+y^2=1,

So after some long computations I get x=(1-t^2)/(1+t^2) and subbing in to get y=2t/(1+t^2)

Now Im using SohCahToa to find the angles ψ andθ but Im not getting the right answer, My computations are correct, so am I doing something wrong?

Thanks