A circle containing a regular pentagon and two equilateral triangles. All shown points are on the circle. What’s the angle α?
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Solution
The angle α is 18°.

Note this is basically the same problem as Eye of the beholder.
Poem
A clear vision
The canopy suspended
Like a rail
Interlacing of loose knots
Of light knots
And fine, protective structure
When it rains
Steel and Iron holding together
Enhancing the skylight
Combining charm with a true
And
Timeless vision
