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Richard Walker

Transit Across a Purple Sun

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This very attractive geometrical puzzle is from Catriona Agg. It looks like there isn't enough information, although there is. See the Comments for my solution.

But even after solving it it still feels as though there is an information deficit somewhere!

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Richard Walker

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Here's my take on it.

SXR103 chemistry is fun (2008) :-)

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I arrived at 36 π by minimising the circle so ending up with the horizontal line being the radius of the purple quarter circle. So area = π (12)2 / 4 = 36 π.  More of an intuitive solution than a rigorous proof.