14: Sine is 2π-periodic, by the rules the given function should be 2π/3-periodic. There is no general rule for absolute value, but the basic period of sine has the shape of two hills, one up and one down, and the absolute value will flip the lower hill up. Thus there is a possibility that the basic shape is in fact half of the sine wave, in other words, we guess the basic period to be half of what we had by rules: T = π/3.

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