A circle divided into six congruent sectors. A smaller concentric circle of radius one quarter of the large one. What fraction is black?

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## Solution

The black fraction is 17/32.

This solution uses the fact that the small sectors are 1/16 of the large ones. Because of rotational symmetry, only one third of the diagram needs to be examined.

## Poem

Radioactivity

Makes love with

The lovely becquerels

Giving generously doses of rays

Silent and invisible enemy

Leading to a full catastrophy

No more romance in Fukushima

No more dance in Hiroshima

Only free and warm Xrays

People dying and fading away