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The image below suggests that there is a small, positive value of x such that

sin(2x)=x

Graph with intersection

  1. Use the small angle approximation to estimate the coordinates of P.

  2. In the image below, y=x has been translated to the right by k units, and y=sin(2x) remains unchanged. Graph with intersection The image suggests that there should be some value of k such that the curves intersect at exactly one small value of x. Approximate the value of k.


For part (a), because 2x is small, you can have

sin(2x)=x2xx

You can square both sides of the equation before rearranging and solving.


For part (b), the translated curve has equation xk.


Square both sides and use the discriminant.