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STEP Support Programme

S3 16 Q7

Hey so I was able to do the preamble bit of the question without too much difficulty but when I get to part (i) I get stuck trying to find neat expressions for |PX2|,|PX3| etc. I have found |OP| = cos(pi/n) and found |PX0| = |PX1| = sin(pi/n) but using cosine rule to find the other lengths creates something that currently looks horrible. Ideas please?

You really should be looking for a link to the stem of the question. In part, we can represent $X_r$ by $w^r$. Then $P$ is either $re^{\pi i /n} = z$ or $re^{i\pi (1 + 1/n) } = x$ where $r = |OP|$.

Now work both cases separately. Can you see how it reduces to the stem of the question? If not, let me know what progress you made.

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