The golden angle is the angle that divides a full angle in a golden ratio (but measured in the opposite direction so that it measures less than 
), i.e.,
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(1)
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(2)
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(3)
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(4)
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(5)
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(6)
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(7)
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(OEIS A131988 and A096627; Livio 2002, p. 112).
It is implemented in the Wolfram Language as GoldenAngle.
van Iterson showed in 1907 that points separated by 
on a tightly bound spiral tends to produce interlocked
spirals winding in opposite directions, and that the number of spirals in these two
families tend to be consecutive Fibonacci numbers
(Livio 2002, p. 112).
Another angle related to the golden ratio is the angle
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(8)
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or twice this angle
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(9)
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the later of which is the smaller interior angle in the golden rhombus.
